Add Forms reporting and the dev lets-talk form definition

[jmgasper]

The Reports portal can now discover forms, read submissions across published and retired revisions, filter by inclusive UTC dates, and download all matching rows as CSV. Reporting remains restricted to the existing reporting roles/scopes; the directory does not grant editing access.

• Add a paginated reporting directory and all-revision submission endpoint with dynamic columns, totals, and validated cursors.
• Stream full CSV exports in 1,000-row batches with one header and existing spreadsheet formula protection. Existing per-version endpoints also accept date filters.
• Add the reviewed lets_talk definition, development-only publication script, and renderer support for Kafka opt-in and hidden attribution answers.
• Document deployment order and extend the dev CORS defaults for Reports and Platform UI. Existing stacks need an explicit CORS parameter update.

Validation: pnpm lint, pnpm build, pnpm typecheck, 36 unit/renderer tests, and 24 integration tests against disposable PostgreSQL. Coverage includes the actual contact definition/Kafka retry path, authorization, revision unions, date boundaries, cursor rejection, and a 1,002-row CSV export.

Rollout: deploy API and existing SubmissionEvent migration, configure Bus API credentials/CORS, publish the dev definition using FORMS_ADMIN_TOKEN, then deploy the companion website and portal changes. No live deployment or form publication was performed. CSV uses an export-start timestamp bound, not a repeatable-read database snapshot. Historical HubSpot submissions are not imported.

Companion PRs: Reports UI and development website.