feat: Enhance search functionality with quality tiers and scoped indexing

- Updated `search_code` function to include a `quality` parameter for search quality tiers: "fast", "balanced", "thorough", and "auto".
- Introduced `search_scope` function to limit search results to a specific directory scope.
- Added `index_scope` function for indexing a specific directory without re-indexing the entire project.
- Refactored `SearchPipeline` to support quality-based routing in the `search` method.
- Implemented `Shard` and `ShardManager` classes to manage multiple index shards with LRU eviction and efficient file routing.
- Added debounce functionality in `IncrementalIndexer` to batch file events and reduce redundant processing.
- Enhanced `FileWatcher` to integrate with `IncrementalIndexer` for improved event handling.

.claude/skills/team-arch-opt/roles/coordinator/role.md

@@ -103,7 +103,7 @@ TEXT-LEVEL ONLY. No source code reading.
 Delegate to @commands/dispatch.md:
 1. Read dependency graph and parallel mode from session.json
 2. Topological sort tasks
-3. Create tasks via TaskCreate with blockedBy
+3. Create tasks via TaskCreate, then set dependencies via TaskUpdate({ addBlockedBy })
 4. Update session.json with task count
 
 ## Phase 4: Spawn-and-Stop