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/pattern/detector.go

@@ -38,21 +38,15 @@ type PatternSyncFunc func(pattern *models.Pattern)
 
 // Detector detects and tracks recurring patterns across observations.
 type Detector struct {
-	config           DetectorConfig
+	ctx              context.Context
 	patternStore     *gorm.PatternStore
 	observationStore *gorm.ObservationStore
-
-	// Vector sync callback
-	syncFunc PatternSyncFunc
-
-	// Candidate tracking (patterns not yet confirmed)
-	candidates   map[string]*candidatePattern
-	candidatesMu sync.RWMutex
-
-	// Background analysis
-	ctx    context.Context
-	cancel context.CancelFunc
-	wg     sync.WaitGroup
+	syncFunc         PatternSyncFunc
+	candidates       map[string]*candidatePattern
+	cancel           context.CancelFunc
+	config           DetectorConfig
+	wg               sync.WaitGroup
+	candidatesMu     sync.RWMutex
 }
 
 // SetSyncFunc sets the callback for syncing patterns to vector store.
@@ -62,11 +56,11 @@ func (d *Detector) SetSyncFunc(fn PatternSyncFunc) {
 
 // candidatePattern tracks a potential pattern before it reaches frequency threshold.
 type candidatePattern struct {
+	patternType    models.PatternType
+	title          string
 	signature      []string
 	observationIDs []int64
 	projects       []string
-	patternType    models.PatternType
-	title          string
 	lastSeenEpoch  int64
 }