#15643: fix(googlechat): DM's works, but groups don't - return add-on action envelope for webhook acks

I couldn't make Google Chat works with groups/spaces (in DM's it worked ok). Creating sample server confirmed json key is working ok for both DM and groups. ## Summary Google Chat add-on interaction payloads (`commonEventObject.hostApp = "CHAT"`) were being accepted and processed, but the webhook ACK response used a bare `{}` body. For add-on flows, Chat expects an action envelope (`hostAppDataAction.chatDataAction`). Returning `{}` can cause the UI to show "Tik not responding" even when the event is processed correctly. This change: - detects add-on payloads in the Google Chat webhook handler - returns a valid add-on ACK envelope: - `{"hostAppDataAction":{"chatDataAction":{}}}` - keeps existing behavior for non-add-on payloads (`{}`) ## Why This avoids false "not responding" errors in Google Chat add-on mode while preserving async processing in OpenClaw. ## Scope - File: `extensions/googlechat/src/monitor.ts` - No config/schema changes - No changes to outbound message logic ## Test Plan - [x] Reproduced issue path with Google Chat add-on payloads (DM + space mention) - [x] Confirmed payloads are delivered to webhook - [x] Confirmed OpenClaw processes events asynchronously after ACK - [x] Verified handler now returns add-on envelope for add-on payloads - [x] Verified non-add-on path still returns `{}` ## Notes This is a compatibility fix for Google Workspace add-on webhook response shape and should be safe for existing Chat API interaction flows. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This change updates the Google Chat webhook handler to return the `hostAppDataAction.chatDataAction` envelope when the incoming request is a Google Workspace Add-on–formatted Chat event (`commonEventObject.hostApp === "CHAT"` with `chat.messagePayload`). For non–Add-on payloads, it continues to return an empty JSON object. This fits the existing design where the webhook acks immediately (HTTP 200) while `processGoogleChatEvent(...)` continues asynchronously in the background, and aligns with the repo’s existing add-on token/issuer support in `extensions/googlechat/src/auth.ts`. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - The change is small, localized to the webhook ack response, preserves prior behavior for non–Workspace Add-on payloads, and is consistent with existing add-on request parsing and auth verification patterns. No correctness or runtime issues were found in the updated logic. - No files require special attention _{Last reviewed commit: 1389179} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->