test(opencode): pin lifecycle invariants for DatabaseEffect + managed-runtime

Adds regression tests for the two non-obvious invariants enforced by the
Effect-Drizzle integration:

- packages/opencode/test/storage/db-effect.test.ts pins that
  DatabaseEffect.layer rebuilds a fresh handle after Database.close + dispose,
  and demonstrates the shared-memoMap poisoning that resetDatabase prevents
  by disposing every DB-consuming runtime before closing the SQLite handle.

- packages/opencode/test/effect/managed-runtime.test.ts pins makeManagedRuntime
  dispose semantics and the lazy.resetIf compare-and-reset guard so a
  rebuilt instance is never clobbered by a stale dispose.