fix(tests): release agent-os SQLite handle before rmSync in server-live

[paopaonyapi-creator]

Summary

• Fix a Windows-only test failure in tests/server-live.test.ts: rmSync(TEST_DIR, { recursive: true }) in the beforeEach/afterEach hooks fails with EBUSY when the process-global agent-os SQLite WAL handle is still open against the test's OPENCODEX_HOME tree.
• startServer wires the generation orchestrator, whose storage lazily opens that handle. On Windows an open file handle keeps the directory busy (Linux silently unlinks the open file, which is why CI never saw this), so every file in the suite reported EBUSY and 0/35 tests could run.
• Call closeAgentOsDbForTests() before touching the test tree in both beforeEach and afterEach, releasing any handle left behind by a previous file in the shared test process.

Verification

• bun run typecheck (bun x tsc --noEmit, strict) — passes with no errors on this branch.
• bun test tests/server-live.test.ts --timeout 20000 — 35 pass / 0 fail / 0 EBUSY (274 expect() calls).
• Baseline before the fix: 0/35 pass, every file hit EBUSY: resource busy or locked on rmSync (Windows).
• Full suite run (scripts/test.ts): tests/server-live.test.ts reports 0 failures; the remaining failure clusters (management-provider-validation, server-images) were reproduced in isolation as pre-existing Windows EBUSY on their own rmSync(TEST_DIR) calls in files this change does not touch.
• No production code changed: 1 file, +10 lines, test-only.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed. (test-only change; no user-facing behavior)
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults. (no auth/secret paths touched)

[github-actions]

✅ Deterministic PR hygiene checks passed.