feat(frontend): Transform layout to use shadcn dashboard-01 with iOS PWA safe area support.

- Replace custom layout with modern SidebarProvider/SidebarInset structure
- Add AppSidebar component using shadcn patterns with preserved account summary
- Add SiteHeader component with SidebarTrigger integration
- Install shadcn sidebar, separator, and related UI components
- Fix iOS PWA safe area issues - sidebar no longer overlaps dynamic island/notch
- Add pt-safe-top and pl-safe-left classes to sidebar and header components
- Remove legacy Sidebar.tsx and Header.tsx components
- Preserve all existing functionality: navigation, API health status, theme toggle, PWA features
- Improve mobile responsive behavior with built-in shadcn drawer patterns

🤖 Generated with [Claude Code](https://claude.ai/code)

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

frontend/package.json

@@ -10,11 +10,25 @@
     "preview": "vite preview"
   },
   "dependencies": {
+    "@dnd-kit/core": "^6.3.1",
+    "@dnd-kit/modifiers": "^9.0.0",
+    "@dnd-kit/sortable": "^10.0.0",
+    "@dnd-kit/utilities": "^3.2.2",
+    "@radix-ui/react-avatar": "^1.1.10",
+    "@radix-ui/react-checkbox": "^1.3.3",
     "@radix-ui/react-dialog": "^1.1.15",
+    "@radix-ui/react-dropdown-menu": "^2.1.16",
+    "@radix-ui/react-label": "^2.1.7",
     "@radix-ui/react-popover": "^1.1.15",
     "@radix-ui/react-progress": "^1.1.7",
     "@radix-ui/react-select": "^2.2.6",
+    "@radix-ui/react-separator": "^1.1.7",
     "@radix-ui/react-slot": "^1.2.3",
+    "@radix-ui/react-tabs": "^1.1.13",
+    "@radix-ui/react-toggle": "^1.1.10",
+    "@radix-ui/react-toggle-group": "^1.1.11",
+    "@radix-ui/react-tooltip": "^1.2.8",
+    "@tabler/icons-react": "^3.35.0",
     "@tailwindcss/forms": "^0.5.10",
     "@tanstack/react-query": "^5.87.1",
     "@tanstack/react-router": "^1.131.36",
@@ -27,15 +41,18 @@
     "cmdk": "^1.1.1",
     "date-fns": "^4.1.0",
     "lucide-react": "^0.542.0",
+    "next-themes": "^0.4.6",
     "postcss": "^8.5.6",
     "react": "^19.1.1",
     "react-day-picker": "^9.10.0",
     "react-dom": "^19.1.1",
-    "recharts": "^3.2.0",
+    "recharts": "^2.15.4",
     "sonner": "^2.0.7",
     "tailwind-merge": "^3.3.1",
     "tailwindcss": "^3.4.17",
-    "tailwindcss-animate": "^1.0.7"
+    "tailwindcss-animate": "^1.0.7",
+    "vaul": "^1.1.2",
+    "zod": "^3.25.76"
   },
   "devDependencies": {
     "@eslint/js": "^9.33.0",