feat(frontend): Phase 1 UX foundation — react-router v6 + responsive AppShell

Atomic foundation for the consensus-approved UX modernization (makes the
platform URL-addressable, refresh-safe, and mobile-usable for hospital demos).

- Migrate hand-rolled useState page switching → react-router v6 (routes.tsx,
  thin App.tsx auth gate, NavLink SideNav, lazy+Suspense per route)
- Add responsive AppShell: persistent rail (lg:) ⇄ off-canvas drawer + hamburger
  (<lg); kills hardcoded ml-[200px]; usable at 375px
- Add ui primitive kit (Skeleton/LoadingState/EmptyState/Card/Panel/Segmented)
- Sweep all raw "加载中..." text loaders → skeleton primitives (G4)
- Centralize test ids (utils/testids.ts); rewrite e2e for URL nav (17/17 pass:
  deep-link, refresh-preserves-page, back, 375px drawer/no-scroll)
- Harden DemographicAnalysis against API shape mismatch (defensive normalize)
- gitignore playwright-report/ and test-results/

Gates: tsc --noEmit 0 · pnpm build ok · e2e 17/17 · grep 加载中 zero outside ui/

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/pnpm-lock.yaml

@@ -26,6 +26,9 @@ importers:
       react-leaflet:
         specifier: ^4.2.1
         version: 4.2.1(leaflet@1.9.4)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
+      react-router-dom:
+        specifier: ^6.30.4
+        version: 6.30.4(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
       recharts:
         specifier: ^2.12.0
         version: 2.15.4(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
@@ -385,6 +388,10 @@ packages:
       react: ^18.0.0
       react-dom: ^18.0.0
 
+  '@remix-run/router@1.23.3':
+    resolution: {integrity: sha512-4An71tdz9X8+3sI4Qqqd2LWd9vS39J7sqd9EU4Scw7TJE/qB10Flv/UuqbPVgfQV9XoK8Np6jNquZitnZq5i+Q==}
+    engines: {node: '>=14.0.0'}
+
   '@rolldown/pluginutils@1.0.0-beta.27':
     resolution: {integrity: sha512-+d0F4MKMCbeVUJwG96uQ4SgAznZNSq93I3V+9NHA4OpvqG8mRCpGdKmK8l/dl02h2CCDHwW2FqilnTyDcAnqjA==}
 
@@ -1504,6 +1511,19 @@ packages:
     resolution: {integrity: sha512-z6F7K9bV85EfseRCp2bzrpyQ0Gkw1uLoCel9XBVWPg/TjRj94SkJzUTGfOa4bs7iJvBWtQG0Wq7wnI0syw3EBQ==}
     engines: {node: '>=0.10.0'}
 
+  react-router-dom@6.30.4:
+    resolution: {integrity: sha512-q4HvNl+mmDdkS0g+MqiBZNteQJCuimWoOyHMy4T/RQLAn9Z29+E91QXRaxOujeMl2HTzRSS0KFPd7lxX3PjV0Q==}
+    engines: {node: '>=14.0.0'}
+    peerDependencies:
+      react: '>=16.8'
+      react-dom: '>=16.8'
+
+  react-router@6.30.4:
+    resolution: {integrity: sha512-SVUsDe+DybHM/WmYKIVYhZh1o5Dcuf16yM6WjG02Q9XVFMZIJyHYhwrr6bFBXZkVP6z69kNkMyBCujt8FaFLJA==}
+    engines: {node: '>=14.0.0'}
+    peerDependencies:
+      react: '>=16.8'
+
   react-smooth@4.0.4:
     resolution: {integrity: sha512-gnGKTpYwqL0Iii09gHobNolvX4Kiq4PKx6eWBCYYix+8cdw+cGo3do906l1NBPKkSWx1DghC1dlWG9L2uGd61Q==}
     peerDependencies:
@@ -2157,6 +2177,8 @@ snapshots:
       react: 18.3.1
       react-dom: 18.3.1(react@18.3.1)
 
+  '@remix-run/router@1.23.3': {}
+
   '@rolldown/pluginutils@1.0.0-beta.27': {}
 
   '@rollup/rollup-android-arm-eabi@4.60.2':
@@ -3233,6 +3255,18 @@ snapshots:
 
   react-refresh@0.17.0: {}
 
+  react-router-dom@6.30.4(react-dom@18.3.1(react@18.3.1))(react@18.3.1):
+    dependencies:
+      '@remix-run/router': 1.23.3
+      react: 18.3.1
+      react-dom: 18.3.1(react@18.3.1)
+      react-router: 6.30.4(react@18.3.1)
+
+  react-router@6.30.4(react@18.3.1):
+    dependencies:
+      '@remix-run/router': 1.23.3
+      react: 18.3.1
+
   react-smooth@4.0.4(react-dom@18.3.1(react@18.3.1))(react@18.3.1):
     dependencies:
       fast-equals: 5.4.0