* fix(googlechat): log webhook auth reject reasons and warn on appPrincipal misconfig
Closes#71078
Webhook auth failures previously returned 401 with no log line, leaving
operators no signal to diagnose. Additionally, app-url audience requires
a numeric OAuth 2.0 client ID as appPrincipal, but a misconfigured email
or empty value silently caused all requests to be rejected.
Changes:
- Log a WARN with accountId and reject reason when verifyGoogleChatRequest fails.
- Add warnAppPrincipalMisconfiguration() called at provider init: warns when
audienceType=app-url and appPrincipal is missing or contains '@'.
Tests: +9 cases in monitor-webhook.test.ts (3 reject-reason scenarios + 4 warner cases).
* fix(googlechat): defer auth rejection logs
* docs: note googlechat webhook auth fix
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Co-authored-by: luyao618 <luyao618@users.noreply.github.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>
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