fix: scope lifecycle notifications to active session, remove mock mode

- Only show hookHistory/lifecycleEvent when viewing the agent's current
  live session, preventing notification leaking to historical sessions
- Reset notifications on SessionStart (like hookHistory already does)
- Remove mock/demo animation mode from SessionLifecycleStatus
- Delete dead useHooksApproval composable (never imported)

server/services/session-state.ts

@@ -322,8 +322,12 @@ class SessionStateManager {
 
     // Build notification
     const notification = buildNotification(payload)
-    const updatedNotifications = [...state.notifications, notification].slice(-MAX_NOTIFICATIONS)
-    patch.notifications = updatedNotifications
+    if (payload.hook_event_name === 'SessionStart') {
+      // Reset notifications on new session, only keep the SessionStart notification
+      patch.notifications = [notification]
+    } else {
+      patch.notifications = [...state.notifications, notification].slice(-MAX_NOTIFICATIONS)
+    }
 
     // Build hook history entry
     const historyEntry: HookHistoryEntry = {