feat(leann-phase2): implement hybrid vector storage and graph-based search

- [x] Add AST-aware code chunking for Go, Python, and TypeScript using tree-sitter
- [x] Implement LEANN-inspired hybrid vector storage with hub detection and selective embedding storage (60-80% savings)
- [x] Add observation relationship graph with CSR format and edge detection (file overlap, semantic similarity, temporal, concept)
- [x] Implement graph-aware search with two-level traversal and relationship-based ranking
- [x] Add auto-tuning system for dynamic hub threshold adjustment based on query performance
- [x] Add comprehensive metrics tracking for vector storage, queries, latency, and graph traversals
- [x] Update configuration system with graph and hybrid storage settings
- [x] Add graph stats and vector metrics endpoints to worker service
- [x] Enhance UI sidebar with advanced metrics display and graph visualization
- [x] Optimize struct field alignment throughout codebase for memory efficiency
- [x] Update documentation with LEANN Phase 2 features and performance benefits
- [x] Add tree-sitter dependency for AST parsing

internal/watcher/watcher.go

@@ -16,15 +16,15 @@ import (
 // Watcher monitors a file or directory for deletion and calls onDelete when removed.
 // It watches the parent directory since fsnotify cannot watch non-existent files.
 type Watcher struct {
-	targetPath string // The file/directory to watch for deletion
-	parentPath string // Parent directory (what we actually watch)
-	onDelete   func() // Callback when target is deleted
-	watcher    *fsnotify.Watcher
 	ctx        context.Context
+	onDelete   func()
+	watcher    *fsnotify.Watcher
 	cancel     context.CancelFunc
+	targetPath string
+	parentPath string
+	debounce   time.Duration
 	mu         sync.Mutex
 	running    bool
-	debounce   time.Duration
 }
 
 // New creates a new Watcher for the given target path.