fix: complete sensing server API, WebSocket connectivity, and mobile tests (#125)

The web UI had persistent 404 errors on model, recording, and training
endpoints, and the sensing WebSocket never connected on Dashboard/Live
Demo tabs because sensingService.start() was only called lazily on
Sensing tab visit.

Server (main.rs):
- Add 14 fully-functional Axum handlers: model CRUD (7), recording
  lifecycle (4), training control (3)
- Scan data/models/ and data/recordings/ at startup
- Recording writes CSI frames to .jsonl via tokio background task
- Model load/unload lifecycle with state tracking

Web UI (app.js):
- Import and start sensingService early in initializeServices() so
  Dashboard and Live Demo tabs connect to /ws/sensing immediately

Mobile (ws.service.ts):
- Fix WebSocket URL builder to use same-origin port instead of
  hardcoded port 3001

Mobile (jest.config.js):
- Fix testPathIgnorePatterns that was ignoring the entire test directory

Mobile (25 test files):
- Replace all it.todo() placeholder tests with real implementations
  covering components, services, stores, hooks, screens, and utils

ADR-043 documents all changes.

ui/mobile/src/__tests__/components/ConnectionBanner.test.tsx

@@ -1,5 +1,36 @@
-describe('placeholder', () => {
-  it('passes', () => {
-    expect(true).toBe(true);
+import React from 'react';
+import { render, screen } from '@testing-library/react-native';
+import { ConnectionBanner } from '@/components/ConnectionBanner';
+import { ThemeProvider } from '@/theme/ThemeContext';
+
+const renderWithTheme = (ui: React.ReactElement) =>
+  render(<ThemeProvider>{ui}</ThemeProvider>);
+
+describe('ConnectionBanner', () => {
+  it('renders LIVE STREAM text when connected', () => {
+    renderWithTheme(<ConnectionBanner status="connected" />);
+    expect(screen.getByText('LIVE STREAM')).toBeTruthy();
+  });
+
+  it('renders DISCONNECTED text when disconnected', () => {
+    renderWithTheme(<ConnectionBanner status="disconnected" />);
+    expect(screen.getByText('DISCONNECTED')).toBeTruthy();
+  });
+
+  it('renders SIMULATED DATA text when simulated', () => {
+    renderWithTheme(<ConnectionBanner status="simulated" />);
+    expect(screen.getByText('SIMULATED DATA')).toBeTruthy();
+  });
+
+  it('renders without crashing for each status', () => {
+    const statuses: Array<'connected' | 'simulated' | 'disconnected'> = [
+      'connected',
+      'simulated',
+      'disconnected',
+    ];
+    for (const status of statuses) {
+      const { unmount } = renderWithTheme(<ConnectionBanner status={status} />);
+      unmount();
+    }
   });
 });