feat: initial Graphile v5 migration - minimal baseline

[pyramation]

feat: initial Graphile v5 migration - minimal baseline

Summary

This PR establishes the foundation for migrating from PostGraphile v4 to v5, including the GraphQL 15→16 upgrade. The approach follows the agreed strategy: disable all plugins and middleware initially to get a minimal working baseline, then incrementally re-enable features.

Core dependency updates:

• graphql: 15.10.1 → ^16.9.0
• postgraphile: ^4.14.1 → ^5.0.0-rc.4
• graphile-build: ^4.14.1 → ^5.0.0-rc.3
• New deps: grafast, grafserv, graphile-config, pg-sql2

Architecture changes:

• graphile-settings rewritten to use v5 preset pattern (PostGraphileAmberPreset)
• graphql/server/middleware/graphile.ts rewritten to use postgraphile() + grafserv for Express integration
• graphql/types/graphile.ts updated with GraphileConfig.Preset pattern
• graphile-cache updated for v5 instance structure
• TypeScript configs updated to use node16 moduleResolution (required for v5 ESM exports)

Temporarily disabled packages (to be migrated incrementally):

• graphql/explorer, graphql/codegen, graphql/test, graphql/react
• graphql/playwright-test, graphql/server-test
• graphile/graphile-test, packages/cli

CI workflow changes:

• Commented out all graphile/* plugin tests (depend on v4 APIs)
• Commented out all graphql/* package tests (depend on v4 server)
• Commented out packages/cli and jobs/knative-job-service tests (depend on graphql packages)

Migration plan documented in docs/plan/graphile-v5-migration.md.

Review & Testing Checklist for Human

• Verify server starts: Run the server locally and confirm it starts without errors. The middleware was completely rewritten and build passing doesn't guarantee runtime correctness.
• Test basic GraphQL query: Execute a simple query against the running server to verify the grafserv integration works.
• Review type casting in graphql/server/src/middleware/graphile.ts lines 52-53: The context function uses (ctx: unknown) with type assertions - verify this matches the actual grafserv context structure.
• Confirm disabled packages are acceptable: 8 packages have builds disabled and ~20 CI test jobs are commented out. Verify this doesn't break any critical workflows.
• Review graphile-settings/src/index.ts: This was rewritten from v4 options to v5 preset pattern - verify the minimal preset configuration is correct.

Recommended test plan:

1. pnpm install && pnpm build (should pass)
2. Start the server with a test database
3. Navigate to /graphiql and run a basic query
4. Verify authentication/context is passed correctly

Notes

The v5 spike repo (constructive-io/graphile) was used as reference for correct patterns but not imported directly.

Link to Devin run: https://app.devin.ai/sessions/0b3cd9962e044fd28cc3cefb5fb61ea4
Requested by: Dan Lynch (@pyramation)

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