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/worker/session/manager.go

@@ -21,11 +21,11 @@ const (
 
 // ObservationData contains data for a tool observation.
 type ObservationData struct {
-	ToolName     string
 	ToolInput    interface{}
 	ToolResponse interface{}
-	PromptNumber int
+	ToolName     string
 	CWD          string
+	PromptNumber int
 }
 
 // SummarizeData contains data for a summarize request.
@@ -36,30 +36,28 @@ type SummarizeData struct {
 
 // PendingMessage represents a message queued for SDK processing.
 type PendingMessage struct {
-	Type        MessageType
 	Observation *ObservationData
 	Summarize   *SummarizeData
+	Type        MessageType
 }
 
 // ActiveSession represents an in-memory active session being processed.
 type ActiveSession struct {
-	SessionDBID            int64
-	ClaudeSessionID        string
-	SDKSessionID           string
+	StartTime              time.Time
+	ctx                    context.Context
+	cancel                 context.CancelFunc
+	notify                 chan struct{}
 	Project                string
 	UserPrompt             string
+	SDKSessionID           string
+	ClaudeSessionID        string
+	pendingMessages        []PendingMessage
 	LastPromptNumber       int
-	StartTime              time.Time
 	CumulativeInputTokens  int64
 	CumulativeOutputTokens int64
-
-	// Concurrency control
-	pendingMessages []PendingMessage
-	messageMu       sync.Mutex
-	notify          chan struct{}
-	ctx             context.Context
-	cancel          context.CancelFunc
-	generatorActive atomic.Bool
+	SessionDBID            int64
+	messageMu              sync.Mutex
+	generatorActive        atomic.Bool
 }
 
 // SessionTimeout is how long an inactive session can exist before cleanup.
@@ -70,15 +68,14 @@ const CleanupInterval = 5 * time.Minute
 
 // Manager manages active session lifecycles.
 type Manager struct {
-	sessionStore *gorm.SessionStore
-	sessions     map[int64]*ActiveSession
-	mu           sync.RWMutex
-	onCreated    func(int64)
-	onDeleted    func(int64)
-	ctx          context.Context
-	cancel       context.CancelFunc
-	// Global notification channel for immediate processing
+	ctx           context.Context
+	sessionStore  *gorm.SessionStore
+	sessions      map[int64]*ActiveSession
+	onCreated     func(int64)
+	onDeleted     func(int64)
+	cancel        context.CancelFunc
 	ProcessNotify chan struct{}
+	mu            sync.RWMutex
 }
 
 // NewManager creates a new session manager.

internal/worker/session/manager_test.go

@@ -669,16 +669,16 @@ func TestActiveSessionCWD(t *testing.T) {
 // TestToolInputResponse tests various tool input/response types.
 func TestToolInputResponse(t *testing.T) {
 	tests := []struct {
-		name     string
 		input    interface{}
 		response interface{}
+		name     string
 	}{
-		{"nil_values", nil, nil},
-		{"string_values", "input string", "response string"},
-		{"map_values", map[string]string{"key": "value"}, map[string]interface{}{"result": true}},
-		{"slice_values", []string{"a", "b"}, []int{1, 2, 3}},
-		{"int_values", 42, 100},
-		{"bool_values", true, false},
+		{name: "nil_values", input: nil, response: nil},
+		{name: "string_values", input: "input string", response: "response string"},
+		{name: "map_values", input: map[string]string{"key": "value"}, response: map[string]interface{}{"result": true}},
+		{name: "slice_values", input: []string{"a", "b"}, response: []int{1, 2, 3}},
+		{name: "int_values", input: 42, response: 100},
+		{name: "bool_values", input: true, response: false},
 	}
 
 	for _, tt := range tests {