feat(agent): adaptive tool timing with slow tool notification

Track per-tool execution time statistics in session metadata. When a tool
call exceeds its adaptive threshold (2x historical max, min 120s default),
send a direct outbound notification to the user.

- ToolTimingMap: parse/serialize/record/threshold from session metadata
- StartSlowTimer: fires once per tool call, auto-cancels on completion
- Team config: slow_tool toggle (default on, always direct, never leader)
- UI: toggle in team settings with i18n (en/vi/zh)
- Store: add GetSessionMetadata to session store interface

internal/store/pg/sessions.go

@@ -142,6 +142,17 @@ func (s *PGSessionStore) SetLabel(key, label string) {
 	}
 }
 
+func (s *PGSessionStore) GetSessionMetadata(key string) map[string]string {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	if data, ok := s.cache[key]; ok && data.Metadata != nil {
+		out := make(map[string]string, len(data.Metadata))
+		maps.Copy(out, data.Metadata)
+		return out
+	}
+	return nil
+}
+
 func (s *PGSessionStore) SetSessionMetadata(key string, metadata map[string]string) {
 	s.mu.Lock()
 	defer s.mu.Unlock()

internal/store/session_store.go

@@ -97,6 +97,7 @@ type SessionStore interface {
 	GetCompactionCount(key string) int
 	GetMemoryFlushCompactionCount(key string) int
 	SetMemoryFlushDone(key string)
+	GetSessionMetadata(key string) map[string]string
 	SetSessionMetadata(key string, metadata map[string]string)
 	SetSpawnInfo(key, spawnedBy string, depth int)
 	SetContextWindow(key string, cw int)