feat(devices): manually add a device by MAC (offline pre-register) → 2.1.3

'+ Add by MAC' in the band header → POST /api/devices → lan_devices.addManual
(status=known, present=false; enriched on next scan). Repo + API + frontend tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/api/devices.test.js

@@ -38,4 +38,19 @@ describe('/api/devices', () => {
   it('PATCH rejects a bad MAC', async () => {
     expect((await owner(request(app).patch('/api/devices/not-a-mac')).send({ name: 'x' })).status).toBe(400);
   });
+
+  it('POST / manually adds an offline device by MAC (owner, lowercased, status=known, absent)', async () => {
+    expect((await request(app).post('/api/devices').send({ mac: 'aa:bb:cc:dd:ee:ff' })).status).toBe(401);
+    const res = await owner(request(app).post('/api/devices')).send({ mac: 'AA:BB:CC:DD:EE:FF', name: 'Garage door', grp: 'Smart Home' });
+    expect(res.status).toBe(201);
+    expect(res.body.mac).toBe('aa:bb:cc:dd:ee:ff');
+    expect(res.body.status).toBe('known');
+    expect(res.body.present).toBe(false);
+    const band = await request(app).get('/api/devices');
+    expect(band.body.groups.find(g => g.name === 'Smart Home').devices.some(d => d.name === 'Garage door')).toBe(true);
+  });
+
+  it('POST / rejects a bad MAC', async () => {
+    expect((await owner(request(app).post('/api/devices')).send({ mac: 'nope' })).status).toBe(400);
+  });
 });