Add backend unit test framework and modularize settings UI

Introduced a Vitest-based backend unit testing framework with supporting scripts, helpers, and GitHub Actions integration. Refactored the admin settings page to a modular architecture, splitting monolithic logic into feature-specific tabs and hooks for improved maintainability and testability. Updated documentation to reflect the new testing setup and settings architecture, and added new dependencies for testing utilities.

tests/utils/job-logger.test.ts

@@ -0,0 +1,47 @@
+/**
+ * Component: Job Logger Utility Tests
+ * Documentation: documentation/backend/services/jobs.md
+ */
+
+import { describe, expect, it, vi } from 'vitest';
+
+const infoMock = vi.fn();
+const warnMock = vi.fn();
+const errorMock = vi.fn();
+const forJobMock = vi.fn(() => ({
+  info: infoMock,
+  warn: warnMock,
+  error: errorMock,
+}));
+
+vi.mock('@/lib/utils/logger', () => ({
+  RMABLogger: {
+    forJob: forJobMock,
+  },
+}));
+
+describe('JobLogger', () => {
+  it('logs info, warn, and error messages via RMABLogger', async () => {
+    const { JobLogger } = await import('@/lib/utils/job-logger');
+    const logger = new JobLogger('job-1', 'Context');
+
+    await logger.info('info message', { foo: 'bar' });
+    await logger.warn('warn message');
+    await logger.error('error message', { error: 'boom' });
+
+    expect(forJobMock).toHaveBeenCalledWith('job-1', 'Context');
+    expect(infoMock).toHaveBeenCalledWith('info message', { foo: 'bar' });
+    expect(warnMock).toHaveBeenCalledWith('warn message', undefined);
+    expect(errorMock).toHaveBeenCalledWith('error message', { error: 'boom' });
+  });
+
+  it('creates a job logger via helper', async () => {
+    const { createJobLogger } = await import('@/lib/utils/job-logger');
+    const logger = createJobLogger('job-2', 'Context2');
+
+    await logger.info('message');
+
+    expect(forJobMock).toHaveBeenCalledWith('job-2', 'Context2');
+    expect(infoMock).toHaveBeenCalledWith('message', undefined);
+  });
+});