jbot: disable local memory in Hermes Agent mode

In Hermes mode JBOT is a pure voice UI — memory is owned by the Agent:
- Backend: sys prompt excludes local memories when backend_mode=hermes
- Backend: config_view now returns backendMode so the frontend can adapt
- Frontend: App.jsx loads backendMode on mount via apiConfig()
- Frontend: memories not passed to apiChat() when isHermesMode
- Frontend: memory extraction (apiExtractMemory) skipped when isHermesMode
- Frontend: MemoryPanel hidden in Hermes mode; replaced by subtle
  '🧠 Hermes Agent 模式 · 记忆由 Agent 管理' badge

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jbot/views.py

@@ -547,7 +547,8 @@ def chat_view(request):
     settings = data.get('settings', {})
     mode     = cfg.get('backend_mode', 'openrouter')
 
-    sys_content = _build_sys_prompt(settings, memories)
+    # In Hermes mode, don't inject local memories — Hermes manages its own memory
+    sys_content = _build_sys_prompt(settings, [] if mode == 'hermes' else memories)
 
     try:
         if mode == 'hermes':
@@ -626,4 +627,5 @@ def config_view(request):
         'volcengine': bool(cfg['volc_app_id'] and cfg['volc_access_token']),
         'llm':        bool(cfg['openrouter_api_key']),
         'ttsVoice':   cfg['volc_tts_voice'],
+        'backendMode': cfg.get('backend_mode', 'openrouter'),
     })