feat: v2 plan — remove autogen/crewai, add tasks and wiki

- Remove autogen and crewai backends (focus on custom only)
- Simplify CLI: remove --backend flag
- Remove optional deps from pyproject.toml
- Add .tasks/ with 7 tasks for Phase 1 refactor
- Add .wiki/concepts/meeting-room-v2.md with architecture plan
- Update .wiki/index.md and .tasks/STATUS.md

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.wiki/index.md

@@ -12,7 +12,8 @@ Catalog of all wiki pages. One line per page, organized by type. Updated on ever
 
 ## Concepts
 
-<!-- (none yet) -->
+- [bootstrap-manifest.md](concepts/bootstrap-manifest.md) — skills used to initialize project structure
+- [meeting-room-v2.md](concepts/meeting-room-v2.md) — v2 architecture: interactive office with Web UI
 
 ## Packages