F2.1d — Add the Postgres and Drizzle metadata seam

[Flow-Fly]

Parent: #133. Grandparent: #132 / #72. Depends on: #265.

Goal

Prove the server can manage a small, reversible Postgres schema through committed Drizzle migrations and report database health.

Scope

• Add Drizzle configuration and a minimal app_meta table.
• Add committed forward migrations and a documented local migration command.
• Add a small database adapter and health check.
• Add local Postgres through Docker Compose.
• Add integration tests against the local database service.
• Document recovery/reset for local development data.

Out of scope

• No user, session, project, entitlement, or billing tables.
• No production database creation or destructive production migration.
• No object storage or deployment.

Acceptance

• A fresh local database can migrate from zero and pass the health check.
• Re-running migrations is safe.
• Server tests exercise the adapter without leaking connections.
• Failure states are explicit and do not report a healthy database.

Risk and routing

Risk: medium because this establishes the migration convention.
Worker-ready: no; refresh the brief against the implemented server skeleton first.
Review need: careful migration and cleanup review.