Docs: Add CHANGELOG, update CLAUDE.md, cleanup old files

- Add CHANGELOG.md with v2.0.0, v1.0.0, v0.1.0 history
- Update CLAUDE.md: v2.0.0 status, learnings section, CI/CD info
- Delete MCP_NORMALIZATION_FIX.md (already implemented)
- Archive start.prompt, start2.prompt to .archive/
- Update .gitignore to exclude .archive/

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

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

.gitignore

@@ -299,3 +299,6 @@ nadlan_mcp/local_settings.py
 
 # Phase summaries should stay in .cursor/plans/ only
 PHASE*.md
+
+# Archived files (historical reference, not tracked)
+.archive/