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/OccupancyGrid.test.tsx

@@ -1,5 +1,62 @@
-describe('placeholder', () => {
-  it('passes', () => {
-    expect(true).toBe(true);
+import React from 'react';
+import { render } from '@testing-library/react-native';
+import { ThemeProvider } from '@/theme/ThemeContext';
+
+jest.mock('react-native-svg', () => {
+  const { View } = require('react-native');
+  return {
+    __esModule: true,
+    default: View,
+    Svg: View,
+    Circle: View,
+    G: View,
+    Text: View,
+    Rect: View,
+    Line: View,
+    Path: View,
+  };
+});
+
+import { OccupancyGrid } from '@/components/OccupancyGrid';
+
+const renderWithTheme = (ui: React.ReactElement) =>
+  render(<ThemeProvider>{ui}</ThemeProvider>);
+
+describe('OccupancyGrid', () => {
+  it('renders without crashing with empty values', () => {
+    const { toJSON } = renderWithTheme(<OccupancyGrid values={[]} />);
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('renders with a full 400-element values array', () => {
+    const values = new Array(400).fill(0.5);
+    const { toJSON } = renderWithTheme(<OccupancyGrid values={values} />);
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('renders with person positions', () => {
+    const values = new Array(400).fill(0.3);
+    const positions = [
+      { x: 5, y: 5 },
+      { x: 15, y: 10 },
+    ];
+    const { toJSON } = renderWithTheme(
+      <OccupancyGrid values={values} personPositions={positions} />,
+    );
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('renders with custom size', () => {
+    const values = new Array(400).fill(0);
+    const { toJSON } = renderWithTheme(
+      <OccupancyGrid values={values} size={200} />,
+    );
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('handles values outside 0-1 range by clamping', () => {
+    const values = [-0.5, 0, 0.5, 1.5, NaN, 2, ...new Array(394).fill(0)];
+    const { toJSON } = renderWithTheme(<OccupancyGrid values={values} />);
+    expect(toJSON()).not.toBeNull();
   });
 });