docs: clean up repo cruft and update all documentation for v0.2.4

- Remove PROMPT.md (AI scaffolding artifact)
- Add .claude/settings* to .gitignore
- Commit .mcp.json (MCP server config)
- Fix ArtifactHub URLs (headlamp/tns-csi path)
- Fix tarball name (tns-csi-VERSION.tar.gz) in all install docs
- Update version URLs from v0.1.0/v0.2.0 to v0.2.4
- Update test count from 67 to 159 across 12 files
- Update Node.js version from 20 to 22
- Add CHANGELOG entry for v0.2.4
- Update testing.md with full test file inventory and CI description

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -92,7 +92,7 @@ Use `agent-organizer` first when a task is large enough to require multiple agen
 All tests must pass before committing:
 
 ```bash
-npm test        # 67 tests across 4 test files
+npm test        # 159 tests across 12 test files
 npm run tsc     # must exit 0
 ```