fix(settings, yjs, ux, ci): default settings, y-leveldb restart resilience, dashboard one-click open, delete error handling, Playwright CI

backend/tests/settings.test.ts

@@ -76,6 +76,26 @@ describe('Settings API', () => {
       expect(body.value).toBe('test-value');
       expect(body.updated_at).toBeDefined();
     });
+
+    it('should return default CAD settings instead of 404', async () => {
+      const defaults = [
+        { key: 'cad.unit', expected: 'mm' },
+        { key: 'cad.gridSize', expected: '20' },
+        { key: 'cad.scaleFactor', expected: '1' },
+      ];
+      for (const { key, expected } of defaults) {
+        const response = await app.inject({
+          method: 'GET',
+          url: `/api/settings/${key}`,
+          headers: { authorization: `Bearer ${authToken}` },
+        });
+        expect(response.statusCode).toBe(200);
+        const body = JSON.parse(response.body);
+        expect(body.key).toBe(key);
+        expect(body.value).toBe(expected);
+        expect(body.updated_at).toBeDefined();
+      }
+    });
   });
 
   // ─── Put (upsert) ───────────────────────────────────