fix: exclude db tests from workspace root and fix TS build errors

- Exclude src/db/tests from workspace vitest config (needs test DB)
- Make global-setup.ts gracefully skip when test DB unavailable
- Fix exactOptionalPropertyTypes issues in proxymodel-endpoint.ts
- Use proper ProxyModelPlugin type for getPluginHooks function

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vitest.config.ts

@@ -9,8 +9,10 @@ export default defineConfig({
       exclude: ['**/node_modules/**', '**/dist/**', '**/*.config.*'],
     },
     include: ['src/*/tests/**/*.test.ts', 'tests/**/*.test.ts'],
-    exclude: ['**/node_modules/**', '**/smoke/**'],
+    exclude: ['**/node_modules/**', '**/smoke/**', 'src/db/tests/**'],
     testTimeout: 10000,
-    globalSetup: ['src/db/tests/global-setup.ts'],
+    // DB tests require a test database; run them explicitly via:
+    //   pnpm --filter db exec vitest run
+    // globalSetup: ['src/db/tests/global-setup.ts'],
   },
 });