chore: update .gitignore with coding agents and test artifacts

[clouatre]

Summary

Updates .gitignore to prevent accidental commits of AI coding assistant files and local development artifacts.

Changes

Added ignore patterns for:

Coding Agents (11 patterns)

• .goose* - Goose AI agent (especially relevant for this repo!)
• .amazonq/ - Amazon Q CLI workspace
• .cursor/ - Cursor AI editor
• .aider* - Aider AI pair programmer
• .bolt/, .claude/, .codex/, .windsurf/ - Other AI tools
• AGENTS.md, CLAUDE.md, opencode.json - AI instruction files

Environment Files (3 patterns)

• .env, .env.local, *.local.env - Secrets and local config

Node.js (1 pattern)

• node_modules/ - For local testing with act or similar tools

Python (3 patterns)

• __pycache__/, .pytest_cache/, *.py[cod] - For testing Python examples

Why

• Prevents accidental commit of AI instructions that could leak sensitive context
• .goose* pattern particularly important since this repo is about Goose
• Avoids committing local secrets and environment variables
• Keeps repository clean from test artifacts
• Matches setup-q-cli-action PR docs: add security documentation and tiered examples #14 pattern

Testing

• ✅ Verified patterns match standard gitignore templates
• ✅ No existing tracked files affected