feat: add Antora and AsciiDoc preview scripts

.gitignore

@@ -1,2 +1,16 @@
 doc/html
 .DS_Store
+
+# Antora build artifacts
+doc/antora_specimen/build/
+doc/antora_specimen/node_modules/
+**/build/site/
+
+# Node.js and npm artifacts
+node_modules/
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Antora cache
+.cache/

DEVELOPMENT.md

@@ -0,0 +1,289 @@
+# BoostLook Development Guide
+
+This guide explains how to develop and test BoostLook styling using two complementary preview workflows: simple AsciiDoc testing and production-like Antora testing.
+
+## Overview
+
+BoostLook provides two preview workflows for developing and testing CSS changes:
+
+- **Preview with AsciiDoc**: Fast iteration with simple AsciiDoc files for quick CSS testing
+- **Preview with Antora**: Comprehensive testing using real Boost documentation content via Antora Specimen
+
+Both workflows provide automatic file watching, rebuilding, and browser preview to streamline your development process.
+
+## Preview Workflows
+
+### Preview with AsciiDoc
+
+**Use Case**: Rapid CSS iteration and basic styling verification
+**Script**: `boostlook_asciidoc_preview.rb`
+**Content**: Your local AsciiDoc files (e.g., `doc/specimen.adoc`)
+**Build System**: Boost.Build (b2)
+**Speed**: Fast, immediate feedback
+
+This workflow monitors AsciiDoc, HTML, and CSS files for changes, automatically rebuilding via Boost.Build and opening the rendered HTML in your browser.
+
+### Preview with Antora
+
+**Use Case**: Realistic testing with actual Boost documentation structure and content
+**Script**: `boostlook_antora_preview.rb`
+**Content**: Real Boost.URL documentation fetched from GitHub
+**Build System**: Antora site generator
+**Speed**: More comprehensive, production-like environment
+
+This workflow uses **Antora Specimen** - a testing setup that fetches official Boost.URL documentation and applies your local BoostLook styling, providing a realistic testing environment with actual production content.
+
+## Prerequisites
+
+### Common Requirements
+- **Ruby** (>= 2.7 recommended)
+- **Listen Gem** – Install via `gem install listen`
+
+### Preview with AsciiDoc Requirements
+
+-   **Asciidoctor Gem**: Install via `gem install asciidoctor`.
+-   **Boost.Build (b2)**: Ensure `b2` is installed and available in your system's `PATH`. You can verify this by running `which b2` or `b2 --version`.
+-   **Boost.Build Configuration (`user-config.jam`)**: This is a critical step. You must tell Boost.Build where to find your `asciidoctor` executable.
+    1.  Find the full path to `asciidoctor` by running:
+        ```sh
+        which asciidoctor
+        ```
+        The output will be a path like `/usr/local/bin/asciidoctor`.
+
+    2.  Create or edit the file `user-config.jam` in your home directory (`$HOME/user-config.jam` on Linux/macOS).
+
+    3.  Add the following line to the file, using the path from step 1:
+        ```jam
+        # Tell Boost.Build where to find the asciidoctor executable
+        using asciidoctor : /usr/local/bin/asciidoctor ;
+        ```
+
+### Preview with Antora Requirements
+- **Node.js** – For Antora CLI
+- **Antora CLI** – Install via `npm install -g @antora/cli @antora/site-generator`
+
+## Quick Start
+
+### Preview with AsciiDoc
+
+1. **Install Prerequisites**:
+   ```bash
+   # Check Ruby installation
+   ruby -v
+
+   # Install required gems
+   gem install asciidoctor listen
+
+   # Verify Boost.Build availability
+   which b2
+   ```
+
+2. **Prepare Content**:
+   - Place AsciiDoc files in the `doc/` directory
+   - Default test file: `doc/specimen.adoc`
+
+3. **Start Preview**:
+   ```bash
+   # From project root
+   ruby boostlook_asciidoc_preview.rb
+   ```
+
+4. **Development Workflow**:
+   - Edit `boostlook.css` or AsciiDoc files in `doc/`
+   - Script automatically detects changes and rebuilds
+   - Browser opens automatically with rendered content
+   - Refresh browser to see changes
+
+### Preview with Antora
+
+1. **Install Prerequisites**:
+   ```bash
+   # Install Antora CLI
+   npm install -g @antora/cli @antora/site-generator
+
+   # Install Ruby gem for file watching
+   gem install listen
+   ```
+
+2. **Start Preview** (with automatic setup):
+   ```bash
+   # Force rebuild and start watching
+   ruby boostlook_antora_preview.rb --rebuild
+   ```
+
+3. **Development Workflow**:
+   - Edit `boostlook.css` → Triggers automatic rebuild
+   - Edit `boostlook.rb` → Triggers automatic rebuild
+   - View changes in browser (auto-opened)
+   - Repeat until styling is perfect
+
+## File Structure
+
+### Preview with AsciiDoc Structure
+```
+boostlook/
+├── boostlook.css                    # Your main CSS file
+├── boostlook.rb                     # Antora extension (Ruby)
+├── boostlook_asciidoc_preview.rb    # AsciiDoc preview script
+└── doc/
+    ├── specimen.adoc                # Test AsciiDoc file
+    └── ...                          # Other AsciiDoc files
+```
+
+### Preview with Antora Structure
+```
+boostlook/
+├── boostlook.css                           # Your main CSS file
+├── boostlook.rb                           # Antora extension (Ruby)
+├── boostlook_antora_preview.rb            # Antora preview script
+└── doc/
+    └── antora_specimen/
+        ├── playbook.yml                   # Antora configuration
+        └── build/                         # Generated site (git-ignored)
+            └── site/
+                ├── index.html             # Entry point
+                └── _/css/
+                    └── boostlook.css      # Your CSS (auto-copied)
+```
+
+## What You're Testing Against
+
+### Preview with AsciiDoc
+- **Content**: Your custom AsciiDoc files
+- **Structure**: Simple document structure
+- **Elements**: Basic typography, code blocks, tables
+- **Speed**: Very fast iteration cycles
+
+### Preview with Antora
+- **Content**: Official Boost.URL documentation from GitHub
+- **Structure**: Actual Antora-generated documentation
+- **Elements**: Real typography, code blocks, tables, navigation, etc.
+- **Complexity**: Multi-level navigation, cross-references, production patterns
+
+## Configuration
+
+### AsciiDoc Preview Configuration
+The AsciiDoc preview uses your existing Boost.Build configuration. Ensure your `build.jam` or similar build files are properly configured for BoostLook integration.
+
+### Antora Preview Configuration (`doc/antora_specimen/playbook.yml`)
+```yaml
+site:
+  title: Boostlook Antora Specimen
+  url: /
+  start_page: url::index.adoc
+
+content:
+  sources:
+    - url: https://github.com/boostorg/url.git
+      branches: develop
+      start_path: doc
+
+ui:
+  bundle:
+    url: https://github.com/boostorg/website-v2-docs/releases/download/ui-master/ui-bundle.zip
+    snapshot: true
+
+output:
+  dir: ./build/site
+```
+
+**Key Points:**
+- **No git submodules** - Content fetched automatically
+- **Remote UI bundle** - Official Boost documentation UI
+- **Your CSS overrides** - Applied automatically after build
+
+## Preview Script Features
+
+### AsciiDoc Preview Features
+- **File Watching**: Monitors `doc/` directory and root CSS files
+- **Automatic Building**: Uses Boost.Build (b2) for rendering
+- **Browser Integration**: Opens rendered HTML automatically
+- **Cross-platform**: Works on macOS, Linux, Windows
+
+### Antora Preview Features
+- **Automatic CSS Override**: Copies your current `boostlook.css` over outdated UI bundle version
+- **Smart Rebuilding**: CSS changes trigger full rebuild (processed by Ruby extension)
+- **Content Fetching**: Automatically downloads latest Boost.URL documentation
+- **File Hash Checking**: Avoids unnecessary rebuilds
+
+## Manual Testing Commands
+
+### Preview with AsciiDoc (Manual)
+```bash
+# Build once without watching
+b2 doc/specimen.html
+
+# Serve locally (if needed)
+python -m http.server 8000
+```
+
+### Preview with Antora (Manual)
+```bash
+# Build once without watching
+cd doc/antora_specimen
+npx antora --fetch playbook.yml
+
+# Copy your current CSS
+cp ../../boostlook.css build/site/_/css/boostlook.css
+
+# Serve locally
+npx http-server build/site -p 8080
+```
+
+## Troubleshooting
+
+### Preview with AsciiDoc Issues
+
+**Error: `error: no generators were found for type 'HTML'`**
+
+- **Cause**: This is the most common issue. It means Boost.Build (`b2`) cannot find the `asciidoctor` executable.
+- **Solution**: You must configure your `$HOME/user-config.jam` file. Please follow the instructions in the **"Boost.Build Configuration (`user-config.jam`)"** section under Prerequisites.
+
+**Error: `command not found: b2`**
+
+- **Cause**: The Boost.Build `b2` executable is not in your system's `PATH`.
+- **Solution**: Install Boost.Build and ensure its location is added to your `PATH`. Verify with `which b2`.
+
+**Script must be run from the project root**
+
+- **Cause**: The script expects to be run from the main `boostlook/` directory.
+- **Solution**: Make sure you are in the project's root directory before running `ruby boostlook_asciidoc_preview.rb`.
+
+**Warnings like `www-browser: not found` or `xdg-open: ... not found`**
+
+- **Cause**: These warnings may appear on some Linux systems if the script cannot find a default command-line web browser.
+- **Solution**: These are usually harmless and can be ignored if a graphical browser still opens. To resolve them, you can install a common utility like `xdg-utils` (`sudo apt-get install xdg-utils` on Debian/Ubuntu).
+
+### Preview with Antora Issues
+
+**Build Fails:**
+```bash
+# Check Antora installation
+npx antora --version
+
+# Check if playbook is valid
+cd doc/antora_specimen
+npx antora playbook.yml --dry-run
+```
+
+**CSS Not Updating:**
+```bash
+# Force complete rebuild
+ruby boostlook_antora_preview.rb --rebuild
+
+# Manually verify CSS copy
+ls -la doc/antora_specimen/build/site/_/css/boostlook.css
+```
+
+**Preview Script Issues:**
+```bash
+# Check if listen gem is installed
+gem list | grep listen
+
+# Install if missing
+gem install listen
+```
+
+**Node.js/Antora Issues:**
+- Ensure Node.js is installed: `node --version`
+- Install/reinstall Antora: `