Add Convex client setup and authentication handling

- Introduced a new module for Convex client configuration in `src/modules/convex.ts`.
- Implemented an authentication token fetcher to manage user tokens.
- Integrated the Convex client into the AuthProvider component in `src/pages/auth/index.tsx`.

package.json

@@ -26,6 +26,7 @@
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "cmdk": "^1.1.1",
+    "convex": "^1.32.0",
     "dayjs": "^1.11.19",
     "es-toolkit": "^1.45.1",
     "fuse.js": "^7.1.0",
@@ -42,6 +43,7 @@
     "access": "public"
   },
   "devDependencies": {
+    "@kevisual/convex": "^0.0.5",
     "@kevisual/kv-login": "^0.1.17",
     "@kevisual/query": "0.0.52",
     "@kevisual/types": "^0.0.12",
@@ -49,7 +51,7 @@
     "@tailwindcss/vite": "^4.2.1",
     "@tanstack/react-router-devtools": "^1.166.2",
     "@tanstack/router-plugin": "^1.166.2",
-    "@types/node": "^25.3.3",
+    "@types/node": "^25.3.5",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^5.1.4",