Keep dev green after moving the active worktree snapshot

The transferred dev snapshot was not publication-ready yet: full tests still
failed because worktree-local docs resolution assumed a repo-root node_modules
tree, some protocol expectations no longer matched the refactored request
bridges, oauth/account-token route tests reused stale modules after resetting
DATA_DIR, and model discovery still fired unawaited default-token writes.

This follow-up makes the moved dev branch self-consistent and green again by
stabilizing module/test isolation, awaiting token mirroring writes, and
aligning narrow tests with the current transformer and request-builder
contracts.

Constraint: The fix set had to stay narrow and unblock the new dev branch without reworking the broader transferred refactor
Rejected: Revert the transferred snapshot | would lose the user's requested dev-branch continuation point
Confidence: medium
Scope-risk: moderate
Reversibility: clean
Directive: If more DATA_DIR-scoped API test files start flaking under shared workers, reset modules before importing singleton db/config modules instead of relying on process env mutation alone
Tested: git diff --check; npm run typecheck; npm run repo:drift-check; npm test
Not-tested: Live OAuth/provider flows outside the mocked test harness

src/server/routes/proxy/architecture-boundaries.test.ts

@@ -100,7 +100,7 @@ describe('proxy route architecture boundaries', () => {
 
   it('keeps codex responses normalization behind transformer helpers', () => {
     const source = readSource('./upstreamEndpoint.ts');
-    expect(source).toContain("from '../../transformers/openai/responses/codexCompatibility.js'");
+    expect(source).toContain("from '../../services/upstreamRequestBuilder.js'");
     expect(source).not.toContain('function ensureCodexResponsesInstructions(');
     expect(source).not.toContain('function ensureCodexResponsesStoreFalse(');
     expect(source).not.toContain('function stripCodexUnsupportedResponsesFields(');

src/server/routes/proxy/gemini.test.ts

@@ -867,7 +867,6 @@ describe('gemini native proxy routes', () => {
     expect(JSON.parse(String(requestInit.body))).toEqual({
       model: 'gpt-4.1',
       stream: false,
-      max_output_tokens: 4096,
       input: [
         {
           type: 'message',