feat(database): brownfield support — introspector, drift detection, db CLI

[ditadi]

🥞 Stacked PR

Use this link to review incremental changes.

• stack/database/foundation [Files changed]
  • stack/database/server [Files changed]
    • stack/database/brownfield [Files changed]
      • stack/database/init [Files changed]
        • stack/database/frontend [Files changed]
          • stack/database/ui [Files changed]
            • stack/database/advanced [Files changed]
              • stack/database/release [Files changed]

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Brownfield support for existing Lakebase/Postgres schemas. This layer lets AppKit inspect a live database, render schema files, detect drift, and manage migrations from the CLI.

Introspection + rendering

Adds the introspector engine, Drizzle adapter, schema-to-introspection bridge, SQL rendering, type mapping, and roundtrip tests.

Drift detection

Adds boot-time drift detection with fatal/warn classifications, production fail-closed behavior for unsafe drift, live-only warnings, healthz saturation, and pg-to-http error mapping.

Database CLI

Adds appkit db introspect, generate, migrate, verify, setup:dev, seed, and migration helpers.

Test plan

• Introspector adapter tests
• Render and roundtrip tests
• Drift tests
• CLI command tests
• Full stack verification run locally before push

Signed-off-by: Victor Ditadi victor.ditadi@databricks.com

PR Stack

1. Database foundation: schema builder, plugin skeleton, runtime base — feat(database): foundation — schema builder, plugin skeleton, connectors #354
2. Server runtime: Drizzle pool, OBO, transactions, hooks — feat(database): server runtime — drizzle pool, OBO, transactions, hooks #355
3. Brownfield support: introspector, drift detection, db CLI (this PR)
4. appkit db init onboarding — feat(cli): appkit db init — one-command lakebase onboarding #357
5. Typed browser db client + dev playground demo — feat(database): typed browser db client + dev playground demo #358
6. React entity UI + columns metadata — feat(database): React entity UI components + columns metadata route #359
7. RLS scaffolder + connection pool tuning — feat(database): RLS scaffolder + connection pool tuning #360
8. Database plugin guide + release polish — docs(database): plugin guide + CLAUDE.md polish + small public-API tweaks #361