Update contribution guide

[davidfowl]

Description

This updates the contribution guide so contributors have current setup, testing, extension, local build, and AI-assisted contribution guidance in one place.

Summary:

• Adds a table of contents for the guide.
• Updates restore and local .NET SDK guidance to match the current global.json behavior.
• Documents how to build and iterate on the VS Code extension, including localization expectations.
• Clarifies Dashboard localization, test filters for quarantined and outerloop tests, and package-only validation.
• Adds guidance for using localhive to create an isolated, fully usable local Aspire build without overwriting the default install.
• Adds AI-assisted contribution expectations for Copilot automatic reviews and the key code-review and pr-testing skills.
• Refreshes stale build, package, and feed examples.

Validation: docs-only change; checked the markdown diff for formatting issues.

Fixes # (issue)

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 17530

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 17530"

[Copilot]

Pull request overview

This docs-only PR refreshes the Aspire contribution guide with current setup, build, testing, localization, extension, local package, localhive, and AI-assisted contribution guidance.

Changes:

• Adds a table of contents and updated repo setup/build guidance.
• Documents VS Code extension build/inner-loop and localization expectations.
• Adds guidance for test filters, package-only validation, localhive, and Aspire PR review/testing skills.

Show a summary per file

File	Description
docs/contributing.md	Updates the contributor guide with refreshed build/test/localization/extension/localhive/AI guidance.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 1

[aspire-repo-bot]

✅ No documentation update needed.

docs_optional → build_or_ci_only

No triggered signals (signal_count == 0; only_test_or_build_changes: true).

The single changed file — docs/contributing.md — is an internal contributor-facing guide under docs/, within the build_or_ci_only allowlist. It contains no user-facing API surface, CLI flags, configuration keys, or behavior that would need to be reflected on microsoft/aspire.dev. No docs PR is needed.