fix: resolve test failures after shared packages migration

Changes:
- Move subprocess-manager tests to @automaker/platform package
  - Tests need to be co-located with source for proper mocking
  - Add vitest configuration to platform package
  - 17/17 platform tests pass

- Update server vitest.config.ts to alias @automaker/* packages
  - Resolve to source files for proper mocking in tests
  - Enables vi.mock() and vi.spyOn() to work correctly

- Fix security.test.ts imports
  - Update dynamic imports from @/lib/security.js to @automaker/platform
  - Module was moved to shared package

- Rewrite prompt-builder.test.ts
  - Use fs/promises mock instead of trying to spy on internal calls
  - 10/10 tests pass

Test Results:
✅ Server: 536/536 tests pass
✅ Platform: 17/17 tests pass

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/server/vitest.config.ts

@@ -32,6 +32,13 @@ export default defineConfig({
   resolve: {
     alias: {
       "@": path.resolve(__dirname, "./src"),
+      // Resolve shared packages to source files for proper mocking in tests
+      "@automaker/utils": path.resolve(__dirname, "../../libs/utils/src/index.ts"),
+      "@automaker/platform": path.resolve(__dirname, "../../libs/platform/src/index.ts"),
+      "@automaker/types": path.resolve(__dirname, "../../libs/types/src/index.ts"),
+      "@automaker/model-resolver": path.resolve(__dirname, "../../libs/model-resolver/src/index.ts"),
+      "@automaker/dependency-resolver": path.resolve(__dirname, "../../libs/dependency-resolver/src/index.ts"),
+      "@automaker/git-utils": path.resolve(__dirname, "../../libs/git-utils/src/index.ts"),
     },
   },
 });