verify_and_parse_webhook exists only on GAuthClient; the route holds
HmacWebhookVerifier + JsonWebhookParser directly, so call verify() and
parse() separately (signature itself was always fine — the AttributeError
landed in the 401 bucket).

Co-Authored-By: Claude Code <noreply@anthropic.com>

Auth off by default (client_id empty). When GHARD_AUTH_CLIENT_ID is set,
the web UI gets a creds-style sign-in gate: splash -> /me -> login screen
(OAuth starts from the click, not page load). Sessions and OAuth state
live in SQLite (survive restarts); webhook endpoint applies global_logout/
profile updates. Scripts/MCP keep working with the Bearer token, agents
keep X-Server-Key ingest. Includes compose env passthrough, README guide.

Co-Authored-By: Claude Code <noreply@anthropic.com>