Add GA4 and Amplitude business event analytics

[Sadturtleman]

Change

Business events now feed GA4 and Amplitude from one authenticated, typed event ledger. The admin dashboard shows each provider's configuration and delivery states. Redash provisioning is removed; existing internal SQL views remain intact.

Amplitude uses independent transactional delivery records, batches of ten, fixed regional endpoints, persisted payloads and insert IDs for retries, and a six-day retry cutoff. Migration 7 adds the queue without changing applied migration 6. No source code, email, inquiry body, or credentials enter analytics payloads.

Validation

• Type checks, 54 regression tests, and production build passed (one external PostgreSQL test skipped locally).
• Browser analytics retry/status test passed.
• GA4 and Amplitude connected in production after user approval; keys are stored in Secret Manager with per-secret access.
• Verified screen/admin events in both GA4 Realtime and Amplitude Live Events, migration 7, and authenticated operational health checks.
• Fixed GA4 numeric client ID fallback based on actual provider validation; added a regression test (9 GA4 tests passed). Four never-collected validation failures were revalidated and retried. Final snapshot: GA4 accepted 8 / Amplitude ingested 8, zero pending or rejected.
• Final deployment: Cloud Build 6c32d5be-84b5-434c-906e-4887bc01cfaa. No PR merge performed.