Add comprehensive .gitignore and update PlatformIO installation docs

## Changes

**Documentation:**
- Update CLAUDE.md with `uv` as recommended PlatformIO installation method
- Add pip3 --break-system-packages as quick alternative
- Explain why uv: 10-100x faster, auto PATH handling, clean environment

**.gitignore:**
- Add PlatformIO build artifacts (.pio/, .vscode/, etc.)
- Add build outputs (*.bin, *.elf, *.map)
- Add Python cache files (__pycache__/, *.pyc, etc.)
- Add IDE and OS files
- Ignore .happy/ tool state directory
- Explicitly ignore bin/arduino-cli (legacy)

**Cleanup:**
- Remove bin/arduino-cli (switched to PlatformIO)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: TianqiYe

.gitignore

@@ -2,3 +2,36 @@
 .claude/settings.backup
 .claude/current_mode
 .claude/agents/
+
+# PlatformIO
+.pio/
+.vscode/
+.pioenvs/
+.piolibdeps/
+
+# Build artifacts
+*.bin
+*.elf
+*.map
+
+# Python
+__pycache__/
+*.pyc
+*.pyo
+.Python
+
+# IDE
+.idea/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Tool state
+.happy/
+
+# Arduino CLI (legacy)
+bin/arduino-cli

CLAUDE.md

@@ -66,11 +66,28 @@ void loop() {
 
 4) Build / Flash (ESP32‑S3) **PLATFORMIO**
 
-## Quick Start
+## Installing PlatformIO (CM5/Raspberry Pi)
+
+**Recommended: Use `uv` (fast & clean)**
 ```bash
-pip install platformio  # One-time install
+# Install uv (modern Python package manager)
+curl -LsSf https://astral.sh/uv/install.sh | sh
+source ~/.bashrc  # Or restart terminal
+
+# Install PlatformIO
+uv tool install platformio
+
+# Verify
+pio --version
 ```
 
+**Alternative: Quick install (works immediately)**
+```bash
+pip3 install platformio --break-system-packages
+```
+
+**Why uv?** 10-100x faster than pip, handles PATH automatically, keeps Python environment clean. It's the modern standard for installing Python CLI tools.
+
 ## Create New Game
 ```bash
 # Create project structure