feat: Implement workflow form handling for paused workflows

- Added module-level storage for pending forms to manage state across sessions.
- Introduced functions to set, get, and clear pending forms with expiration handling.
- Enhanced DifyServiceAPIRunner to support resuming paused workflows via form actions.
- Implemented logic to yield human input requests and display appropriate messages.
- Updated workflow submission methods to handle paused states and resume actions.
- Ensured proper merging of pending form actions with user inputs for seamless interaction.

src/langbot/pkg/platform/botmgr.py

@@ -501,6 +501,8 @@ class PlatformManager:
             bot_entity.adapter_config,
             logger,
         )
+        if hasattr(adapter_inst, 'ap'):
+            adapter_inst.ap = self.ap
 
         # 如果 adapter 支持 set_bot_uuid 方法，设置 bot_uuid（用于统一 webhook）
         if hasattr(adapter_inst, 'set_bot_uuid'):