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

distribution/claude-plugin/.mcp.json

@@ -0,0 +1,6 @@
+{
+  "skill-seekers": {
+    "command": "python",
+    "args": ["-m", "skill_seekers.mcp.server_fastmcp"]
+  }
+}