Fix desktop responsive layout: sidebar, content sizing, remove duplicate tab bar

- Replace uni-app custom-tab-bar with manual NavBar component in App.vue
  (uni-app auto-detection was not including component in build)
- Mobile: NavBar hidden via CSS display:none, uni-app default tab bar handles nav
- Desktop: NavBar visible as 220px left sidebar, uni-app tab bar hidden
- Content area: max-width 1200px with margin-left:220px, centered
- Buttons/inputs/cards: global desktop CSS overrides for reasonable sizing
- Clean approach: NavBar always in DOM, CSS media queries control visibility
  (no v-if, no conflicting !important)

uni-app/src/pages.json

@@ -111,7 +111,7 @@
     "backgroundColor": "#f5f5f5"
   },
   "tabBar": {
-    "custom": true,
+    "custom": false,
     "color": "#666666",
     "selectedColor": "#1890ff",
     "backgroundColor": "#ffffff",