feat(backend): add GET /api/bootstrap route + test

- Returns productId, displayName, backendPort for client bootstrapping
- Integration test validates response shape and types

backend/src/diagnostics.test.ts

@@ -4,7 +4,7 @@ import type { FastifyInstance } from 'fastify';
 import { getAllFlags } from './lib/feature-flags.js';
 import { getBufferedEvents, flushEvents } from './lib/telemetry.js';
 import { config } from './lib/config.js';
-import { PRODUCT_ID } from './lib/product-config.js';
+import { PRODUCT_ID, productConfig } from './lib/product-config.js';
 
 let app: FastifyInstance;
 
@@ -29,6 +29,11 @@ beforeAll(async () => {
     timestamp: new Date().toISOString(),
     requestId: req.id,
   }));
+  app.get('/api/bootstrap', async () => ({
+    productId: productConfig.productId,
+    displayName: productConfig.displayName,
+    backendPort: config.PORT,
+  }));
   await app.ready();
 });
 
@@ -84,4 +89,16 @@ describe('diagnostics routes', () => {
     expect(body).toHaveProperty('timestamp');
     expect(body.timestamp).toMatch(/^\d{4}-\d{2}-\d{2}T/);
   });
+
+  it('GET /api/bootstrap returns product identity', async () => {
+    const res = await app.inject({ method: 'GET', url: '/api/bootstrap' });
+    expect(res.statusCode).toBe(200);
+    const body = res.json();
+    expect(body).toHaveProperty('productId');
+    expect(body).toHaveProperty('displayName');
+    expect(body).toHaveProperty('backendPort');
+    expect(typeof body.productId).toBe('string');
+    expect(typeof body.displayName).toBe('string');
+    expect(typeof body.backendPort).toBe('number');
+  });
 });

backend/src/server.ts

@@ -17,7 +17,7 @@ import { initDatastore } from './lib/datastore.js';
 import { config } from './lib/config.js';
 import { getAllFlags } from './lib/feature-flags.js';
 import { getBufferedEvents, flushEvents } from './lib/telemetry.js';
-import { PRODUCT_ID } from './lib/product-config.js';
+import { PRODUCT_ID, productConfig } from './lib/product-config.js';
 
 import { jwtVerify } from 'jose';
 import type { JwtPayload } from './lib/request-context.js';
@@ -53,6 +53,13 @@ await app.register(householdRoutes, { prefix: '/api' });
 await app.register(sharedTimerRoutes, { prefix: '/api' });
 await app.register(webhookRoutes, { prefix: '/api' });
 
+// ── Bootstrap (no auth) ──────────────────────────────────────────
+app.get('/api/bootstrap', async () => ({
+  productId: productConfig.productId,
+  displayName: productConfig.displayName,
+  backendPort: config.PORT,
+}));
+
 // ── Diagnostics routes (no auth) ────────────────────────────────
 app.get('/api/diagnostics/flags', async () => getAllFlags());
 app.get('/api/diagnostics/telemetry', async () => ({ events: getBufferedEvents() }));