feat(config): make BASE_URL a required field and update related documentation

backend/app/api/board_group_memory.py

@@ -331,7 +331,7 @@ async def _notify_group_memory_targets(
     if len(snippet) > MAX_SNIPPET_LENGTH:
         snippet = f"{snippet[: MAX_SNIPPET_LENGTH - 3]}..."
 
-    base_url = settings.base_url or "http://localhost:8000"
+    base_url = settings.base_url
 
     context = _NotifyGroupContext(
         session=session,

backend/app/api/board_memory.py

@@ -191,7 +191,7 @@ async def _notify_chat_targets(
     snippet = memory.content.strip()
     if len(snippet) > MAX_SNIPPET_LENGTH:
         snippet = f"{snippet[: MAX_SNIPPET_LENGTH - 3]}..."
-    base_url = settings.base_url or "http://localhost:8000"
+    base_url = settings.base_url
     for agent in targets.values():
         if not agent.openclaw_session_id:
             continue

backend/app/api/board_onboarding.py

@@ -229,7 +229,7 @@ async def start_onboarding(
         return onboarding
 
     dispatcher = BoardOnboardingMessagingService(session)
-    base_url = settings.base_url or "http://localhost:8000"
+    base_url = settings.base_url
     prompt = (
         "BOARD ONBOARDING REQUEST\n\n"
         f"Board Name: {board.name}\n"