feat: add distribution files for Smithery, GitHub Action, and Claude Code Plugin

- Add Claude Code Plugin: plugin.json, .mcp.json, 3 slash commands, skill-builder agent skill
- Add GitHub Action: composite action.yml with 6 inputs/2 outputs, comprehensive README
- Add Smithery: publishing guide with namespace yusufkaraaslan/skill-seekers created
- Add render-mcp.yaml for MCP server deployment on Render
- Fix Dockerfile.mcp: --transport flag (nonexistent) → --http, add dynamic PORT support
- Update AGENTS.md to v3.3.0 with corrected test count and expanded CI section
- Allow distribution/claude-plugin/.mcp.json in .gitignore

.gitignore

@@ -61,5 +61,6 @@ htmlcov/
 skill-seekers-configs/
 .claude/skills
 .mcp.json
+!distribution/claude-plugin/.mcp.json
 settings.json
 USER_GUIDE.md