feat: refactor theme management and remove next-themes dependency

- Replaced the next-themes package with a custom ThemeProvider component for enhanced theme management.
- Implemented local storage handling for theme persistence and system theme detection.
- Updated the Toaster component to utilize the new theme context.
- Removed unused next-themes references from package.json and package-lock.json.

package-lock.json

@@ -7,6 +7,7 @@
     "": {
       "name": "mmapp",
       "version": "0.1.0",
+      "hasInstallScript": true,
       "workspaces": [
         "packages/*",
         "backend"
@@ -18,7 +19,6 @@
         "clsx": "^2.1.1",
         "lucide-react": "^1.11.0",
         "next": "16.2.4",
-        "next-themes": "^0.4.6",
         "react": "19.2.4",
         "react-dom": "19.2.4",
         "shadcn": "^4.5.0",
@@ -9017,16 +9017,6 @@
         }
       }
     },
-    "node_modules/next-themes": {
-      "version": "0.4.6",
-      "resolved": "https://registry.npmjs.org/next-themes/-/next-themes-0.4.6.tgz",
-      "integrity": "sha512-pZvgD5L0IEvX5/9GWyHMf3m8BKiVQwsCMHfoFosXtXBMnaS0ZnIJ9ST4b4NqLVKDEm8QBxoNNGNaBv2JNF6XNA==",
-      "license": "MIT",
-      "peerDependencies": {
-        "react": "^16.8 || ^17 || ^18 || ^19 || ^19.0.0-rc",
-        "react-dom": "^16.8 || ^17 || ^18 || ^19 || ^19.0.0-rc"
-      }
-    },
     "node_modules/next/node_modules/@next/swc-win32-x64-msvc": {
       "version": "16.2.4",
       "resolved": "https://registry.npmjs.org/@next/swc-win32-x64-msvc/-/swc-win32-x64-msvc-16.2.4.tgz",
@@ -12684,21 +12674,6 @@
       "dependencies": {
         "zod": "^4.4.1"
       }
-    },
-    "node_modules/@next/swc-win32-x64-msvc": {
-      "version": "16.2.4",
-      "resolved": "https://registry.npmjs.org/@next/swc-win32-x64-msvc/-/swc-win32-x64-msvc-16.2.4.tgz",
-      "integrity": "sha512-kMVGgsqhO5YTYODD9IPGGhA6iprWidQckK3LmPeW08PIFENRmgfb4MjXHO+p//d+ts2rpjvK5gXWzXSMrPl9cw==",
-      "cpu": [
-        "x64"
-      ],
-      "optional": true,
-      "os": [
-        "win32"
-      ],
-      "engines": {
-        "node": ">= 10"
-      }
     }
   }
 }