refactor: convert frontend from submodule to true monorepo

Convert frontend from Git submodule to a regular monorepo directory for simplified development workflow.

Changes:
- Remove frontend submodule tracking (mode 160000 gitlink)
- Add all frontend source files directly to main repository
- Remove frontend/.git directory
- Update CLAUDE.md to clarify true monorepo structure
- Update Frontend Architecture documentation (React Router v6, Socket.IO, Leaflet, ErrorBoundary)

Benefits of Monorepo:
- Single git clone for entire project
- Unified commit history
- Simpler CI/CD pipeline
- Easier for new developers
- No submodule sync issues
- Atomic commits across frontend and backend

Frontend Files Added:
- All React components (MapView, ErrorBoundary, TaskList, SocialFeed, etc.)
- Context providers (AuthContext, SocketContext)
- Complete test suite with MSW
- Dependencies and configuration files

Branch Cleanup:
- Using 'main' as default branch (develop deleted)
- Frontend no longer has separate Git history

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

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

frontend/src/setupTests.js

@@ -0,0 +1,62 @@
+// jest-dom adds custom jest matchers for asserting on DOM nodes.
+// allows you to do things like:
+// expect(element).toHaveTextContent(/react/i)
+// learn more: https://github.com/testing-library/jest-dom
+import '@testing-library/jest-dom';
+
+// MSW (Mock Service Worker) for API mocking
+import { server } from './mocks/server';
+
+// Establish API mocking before all tests
+beforeAll(() => server.listen({ onUnhandledRequest: 'warn' }));
+
+// Reset any request handlers that we may add during the tests,
+// so they don't affect other tests
+afterEach(() => server.resetHandlers());
+
+// Clean up after the tests are finished
+afterAll(() => server.close());
+
+// Mock localStorage
+const localStorageMock = {
+  getItem: jest.fn(),
+  setItem: jest.fn(),
+  removeItem: jest.fn(),
+  clear: jest.fn(),
+};
+global.localStorage = localStorageMock;
+
+// Mock window.matchMedia (used by some components)
+Object.defineProperty(window, 'matchMedia', {
+  writable: true,
+  value: jest.fn().mockImplementation(query => ({
+    matches: false,
+    media: query,
+    onchange: null,
+    addListener: jest.fn(), // Deprecated
+    removeListener: jest.fn(), // Deprecated
+    addEventListener: jest.fn(),
+    removeEventListener: jest.fn(),
+    dispatchEvent: jest.fn(),
+  })),
+});
+
+// Suppress console errors during tests (except actual errors)
+const originalError = console.error;
+beforeAll(() => {
+  console.error = (...args) => {
+    if (
+      typeof args[0] === 'string' &&
+      (args[0].includes('Warning: ReactDOM.render') ||
+       args[0].includes('Warning: useLayoutEffect') ||
+       args[0].includes('Not implemented: HTMLFormElement.prototype.submit'))
+    ) {
+      return;
+    }
+    originalError.call(console, ...args);
+  };
+});
+
+afterAll(() => {
+  console.error = originalError;
+});