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/SparklineChart.test.tsx

@@ -1,5 +1,54 @@
-describe('placeholder', () => {
-  it('passes', () => {
-    expect(true).toBe(true);
+import React from 'react';
+import { render } from '@testing-library/react-native';
+import { SparklineChart } from '@/components/SparklineChart';
+import { ThemeProvider } from '@/theme/ThemeContext';
+
+const renderWithTheme = (ui: React.ReactElement) =>
+  render(<ThemeProvider>{ui}</ThemeProvider>);
+
+describe('SparklineChart', () => {
+  it('renders without crashing with data points', () => {
+    const { toJSON } = renderWithTheme(
+      <SparklineChart data={[-50, -45, -48, -42, -47]} />,
+    );
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('renders with empty data array', () => {
+    const { toJSON } = renderWithTheme(<SparklineChart data={[]} />);
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('renders with single data point', () => {
+    const { toJSON } = renderWithTheme(<SparklineChart data={[42]} />);
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('renders with custom color', () => {
+    const { toJSON } = renderWithTheme(
+      <SparklineChart data={[1, 2, 3]} color="#FF0000" />,
+    );
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('renders with custom height', () => {
+    const { toJSON } = renderWithTheme(
+      <SparklineChart data={[1, 2, 3]} height={100} />,
+    );
+    expect(toJSON()).not.toBeNull();
+  });
+
+  it('has an image accessibility role', () => {
+    const { getByRole } = renderWithTheme(
+      <SparklineChart data={[1, 2, 3]} />,
+    );
+    expect(getByRole('image')).toBeTruthy();
+  });
+
+  it('renders with all identical values', () => {
+    const { toJSON } = renderWithTheme(
+      <SparklineChart data={[5, 5, 5, 5, 5]} />,
+    );
+    expect(toJSON()).not.toBeNull();
   });
 });