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/scoring/recalculator.go

@@ -21,13 +21,13 @@ type ObservationStore interface {
 
 // Recalculator periodically recalculates importance scores for observations.
 type Recalculator struct {
+	log        zerolog.Logger
 	store      ObservationStore
 	calculator *Calculator
-	log        zerolog.Logger
-	interval   time.Duration
-	batchSize  int
 	stopCh     chan struct{}
 	doneCh     chan struct{}
+	interval   time.Duration
+	batchSize  int
 	mu         sync.Mutex
 	running    bool
 }

internal/scoring/recalculator_test.go

@@ -16,14 +16,14 @@ import (
 
 // MockObservationStore is a mock implementation of ObservationStore for testing.
 type MockObservationStore struct {
-	mu                sync.Mutex
-	observations      []*models.Observation
-	scores            map[int64]float64
-	conceptWeights    map[string]float64
 	updateErr         error
 	getErr            error
 	getConceptsErr    error
+	scores            map[int64]float64
+	conceptWeights    map[string]float64
+	observations      []*models.Observation
 	updateScoresCalls int
+	mu                sync.Mutex
 }
 
 func NewMockObservationStore() *MockObservationStore {