feat(build-runtime): add canonical runtime adapter registry

[kubohiroya]

Summary

• add the canonical build runtime adapter contract, typed runtime errors, runtime record validation, revision tracking, and record projector
• wire the app worker runtime through a shape adapter registry behind the default-off VITE_CANONICAL_BUILD_RUNTIME_ADAPTER flag
• document the runtime adapter boundary/flag and update runtime record fixtures for the required nodeType

Scope

This is the first checkpoint for #1503. It establishes the shared contract/registry and flag-gated app wiring; location/route runtime adapters and legacy surface removal remain follow-up work under #1503.

Verification

• pnpm vitest run packages/build-api/src/__tests__/CanonicalBuildRuntimeAdapter.contract.unit.test.ts packages/build-runtime-services/src/__tests__/CanonicalBuildRuntimeAdapterRegistry.unit.test.ts
• pnpm vitest run src/config/__tests__/canonicalBuildFeatureFlags.unit.test.ts (from app)
• pnpm -w turbo run typecheck --filter @hierarchidb/build-api --filter @hierarchidb/build-runtime-services --filter @hierarchidb/app
• pnpm --filter @hierarchidb/app test
• pnpm --filter @hierarchidb/app format:check
• pnpm exec biome check packages/build-api/src packages/build-runtime-services/src --reporter summary
• pnpm exec biome check packages/build-runtime-services/src app/src/worker-runtime/workerBootstrapUtils.ts --reporter summary
• git diff --check

Refs #1503