Adds a credential hint box directly in the Tink Link connection UI
showing username (u04877810) and password (vxw774) with copy buttons.
No more hunting in Tink Console during a demo.
- Replace /events/v2/* endpoints (404 in sandbox) with /api/v1/webhooks
- Add list_webhooks() and register_webhook() methods to TinkClient
- Step 6 now shows: webhook flow diagram + curl examples + live API + sample payload
- Handle sandbox 404 gracefully (shows example data, no red error)
- Remove .env.production from git tracking (credentials via Gitea secrets)
- deploy.yml: write .env.production from TINK_CLIENT_ID/SECRET secrets
