chore: Project cleanup and Canvas UX improvements (Phase 7-9)

## Cleanup (v0.5.0)
- Delete 102+ orphaned MCP session temp files
- Remove build artifacts (htmlcov, dist, __pycache__)
- Archive superseded plan docs (RALPH_LOOP V2/V3, CANVAS V3, etc.)
- Move debug/analysis scripts from tests/ to tools/analysis/
- Archive redundant NX journals to archive/nx_journals/
- Archive monolithic PROTOCOL.md to docs/archive/
- Update .gitignore with missing patterns
- Clean old study files (optimization_log_old.txt, run_optimization_old.py)

## Canvas UX (Phases 7-9)
- Phase 7: Resizable panels with localStorage persistence
  - Left sidebar: 200-400px, Right panel: 280-600px
  - New useResizablePanel hook and ResizeHandle component
- Phase 8: Enable all palette items
  - All 8 node types now draggable
  - Singleton logic for model/solver/algorithm/surrogate
- Phase 9: Solver configuration
  - Add SolverEngine type (nxnastran, mscnastran, python, etc.)
  - Add NastranSolutionType (SOL101-SOL200)
  - Engine/solution dropdowns in config panel
  - Python script path support

## Documentation
- Update CHANGELOG.md with recent versions
- Update docs/00_INDEX.md
- Create examples/README.md
- Add docs/plans/CANVAS_UX_IMPROVEMENTS.md

docs/00_INDEX.md

@@ -1,7 +1,7 @@
 # Atomizer Documentation Index
 
-**Last Updated**: 2026-01-20
-**Project Version**: 1.0.0 (AtomizerSpec v2.0 - Full LLM Integration)
+**Last Updated**: 2026-01-24
+**Project Version**: 0.5.0 (AtomizerSpec v2.0 - Canvas Builder)
 
 ---
 
@@ -201,6 +201,8 @@ Historical documents are preserved in `archive/`:
 - `archive/historical/` - Legacy documents, old protocols
 - `archive/marketing/` - Briefings, presentations
 - `archive/session_summaries/` - Past development sessions
+- `archive/plans/` - Superseded plan documents (RALPH_LOOP V2/V3, CANVAS V3, etc.)
+- `archive/PROTOCOL_V1_MONOLITHIC.md` - Original monolithic protocol (Nov 2025)
 
 ---
 
@@ -216,5 +218,5 @@ For Claude/AI integration:
 
 ---
 
-**Last Updated**: 2026-01-20
+**Last Updated**: 2026-01-24
 **Maintained By**: Antoine / Atomaste