feat(v2.3.0): Add multi-agent installation support

Add automatic skill installation to 10+ AI coding agents with a single command.

New Features:
- New install-agent command for installing skills to any AI agent
- Support for 10+ agents: Claude Code, Cursor, VS Code, Amp, Goose, OpenCode, Letta, Aide, Windsurf
- Smart path resolution (global ~/.agent vs project-relative .agent/)
- Fuzzy agent name matching with suggestions
- --agent all flag to install to all agents at once
- --force flag to overwrite existing installations
- --dry-run flag to preview installations
- Comprehensive error handling and user feedback

Implementation:
- Created install_agent.py (379 lines) with core installation logic
- Updated main.py with install-agent subcommand
- Updated pyproject.toml with entry point
- Added 32 comprehensive tests (all passing, 603 total)
- No regressions in existing functionality

Documentation:
- Updated README.md with multi-agent installation guide
- Updated CLAUDE.md with install-agent examples
- Updated CHANGELOG.md with v2.3.0 release notes
- Added agent compatibility table

Technical Details:
- 100% own implementation (no external dependencies)
- Pure Python using stdlib (shutil, pathlib, argparse)
- Compatible with Agent Skills open standard (agentskills.io)
- Works offline

Closes #210

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "skill-seekers"
-version = "2.2.0"
+version = "2.3.0"
 description = "Convert documentation websites, GitHub repositories, and PDFs into Claude AI skills"
 readme = "README.md"
 requires-python = ">=3.10"
@@ -110,6 +110,7 @@ skill-seekers-package = "skill_seekers.cli.package_skill:main"
 skill-seekers-upload = "skill_seekers.cli.upload_skill:main"
 skill-seekers-estimate = "skill_seekers.cli.estimate_pages:main"
 skill-seekers-install = "skill_seekers.cli.install_skill:main"
+skill-seekers-install-agent = "skill_seekers.cli.install_agent:main"
 
 [tool.setuptools]
 packages = ["skill_seekers", "skill_seekers.cli", "skill_seekers.mcp", "skill_seekers.mcp.tools"]