feat: add comprehensive test suite and CI pipeline

- Add 402 unit tests with 61.7% code coverage
- Add Vitest configuration with coverage reporting
- Extract testable utility functions from services
- Create test.yml workflow (runs on PR and push to main)
- Update docker-build.yml to require tests before building
- Add scheduler-utils.ts and server-config.ts for testable code

Test files added:
- auth.test.ts, medications.test.ts, planner.test.ts
- settings.test.ts, doses.test.ts, share.test.ts
- database.test.ts, server.test.ts, services.test.ts
- env.test.ts, translations.test.ts, integration.test.ts
- e2e-routes.test.ts, stock-calculation.test.ts

.github/workflows/docker-build.yml

@@ -27,7 +27,18 @@ env:
   REGISTRY: ghcr.io
 
 jobs:
+  # =============================================================================
+  # Run Tests First (reuse test workflow)
+  # =============================================================================
+  test:
+    name: Run Tests
+    uses: ./.github/workflows/test.yml
+
+  # =============================================================================
+  # Build and Push Docker Images (only after tests pass)
+  # =============================================================================
   build-and-push:
+    needs: test
     runs-on: ubuntu-latest
     permissions:
       contents: read