feat: scaffold tailwind + shadcn foundation, swap to next-themes

Installs Tailwind CSS v3, postcss, autoprefixer, next-themes, lucide-react,
clsx, tailwind-merge, class-variance-authority, sonner, and tailwindcss-animate.
Creates tailwind.config.ts, postcss.config.mjs, components.json, src/lib/utils.ts
(cn helper), replaces globals.css with CSS variable theme, adds
suppressHydrationWarning to html element, and replaces MUI ThemeProvider
with next-themes ThemeProvider + sonner Toaster. MUI remains installed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -26,28 +26,36 @@
     "@mui/material": "^7.3.9",
     "@mui/x-date-pickers": "^8.27.2",
     "apexcharts": "^5.10.4",
+    "autoprefixer": "^10.4.27",
     "bcryptjs": "^3.0.3",
+    "class-variance-authority": "^0.7.1",
+    "clsx": "^2.1.1",
     "d3-geo": "^3.1.1",
     "dayjs": "^1.11.20",
     "drizzle-orm": "^0.45.1",
+    "lucide-react": "^0.577.0",
     "maplibre-gl": "^5.20.1",
     "maxmind": "^5.0.5",
     "next": "^16.1.7",
     "next-auth": "^5.0.0-beta.30",
+    "next-themes": "^0.4.6",
     "node-forge": "^1.3.3",
+    "postcss": "^8.5.8",
     "react": "^19.2.4",
     "react-apexcharts": "^2.1.0",
     "react-dom": "^19.2.4",
     "react-map-gl": "^8.1.0",
+    "sonner": "^2.0.7",
+    "tailwind-merge": "^3.5.0",
+    "tailwindcss": "^3.4.19",
     "topojson-client": "^3.1.0"
   },
   "devDependencies": {
-    "@types/better-sqlite3": "^7.6.13",
-    "@types/bun": "latest",
     "@eslint/js": "^10.0.1",
-    "better-sqlite3": "^12.8.0",
     "@next/eslint-plugin-next": "^16.1.7",
     "@playwright/test": "^1.58.2",
+    "@types/better-sqlite3": "^7.6.13",
+    "@types/bun": "latest",
     "@types/d3-geo": "^3.1.0",
     "@types/node": "^25.5.0",
     "@types/node-forge": "^1.3.14",
@@ -55,8 +63,10 @@
     "@types/react-dom": "^19.2.3",
     "@types/topojson-client": "^3.1.5",
     "@vitest/ui": "^4.1.0",
+    "better-sqlite3": "^12.8.0",
     "drizzle-kit": "^0.31.10",
     "eslint": "^10.0.3",
+    "tailwindcss-animate": "^1.0.7",
     "typescript": "^5.9.3",
     "typescript-eslint": "^8.57.1",
     "vite-tsconfig-paths": "^6.1.1",