support standalone (.shr) activity download via form version

Branch download by the card form 'version' field: standalone packs a flat .shr (no xbot_robot/xbot_extensions, no internal deps), private keeps the current .bot. Also enable kaniko layer cache to skip pip install on code-only builds.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/__init__.py

@@ -166,9 +166,12 @@ def do_card_action_trigger(data: P2CardActionTrigger) -> P2CardActionTriggerResp
     # data = json.loads(lark.JSON.marshal(data))
     open_id = data.event.operator.open_id
     activity_name = data.event.action.form_value.get("select_activity")
+    package_type = data.event.action.form_value.get("version") or "private"
     open_message_id = data.event.context.open_message_id
 
-    process_push_xbot_activity_bot.delay(activity_name, open_id, open_message_id)
+    process_push_xbot_activity_bot.delay(
+        activity_name, open_id, open_message_id, package_type
+    )
     resp = {"toast": {"type": "info", "content": "提交成功, 机器人即将推送"}}
     return P2CardActionTriggerResponse(resp)