Frontend: land deferred major upgrades (Clerk 7, Tailwind 4, lucide-react 1) (#24)

* Upgrade Clerk 6 -> 7 in frontend

- SignedIn/SignedOut replaced with Show when="signed-in"/"signed-out"
- ClerkProvider afterSignInUrl/afterSignUpUrl -> signInFallbackRedirectUrl/signUpFallbackRedirectUrl

Co-authored-by: Rishi Desai <RishiDesai@users.noreply.github.com>

* Upgrade lucide-react 0.468.0 -> 1.9.0; inline Github icon

Brand icons (Github, Twitter, etc.) removed in lucide-react v1.
Added a minimal inline SVG GithubIcon component used on the
landing page; ArrowRight still comes from lucide-react.

Co-authored-by: Rishi Desai <RishiDesai@users.noreply.github.com>

* Upgrade Tailwind CSS 3 -> 4

- Run official @tailwindcss/upgrade codemod across templates and CSS
- Drop tailwind.config.ts; theme tokens moved into @theme block in
  src/app/globals.css
- postcss.config.mjs now uses @tailwindcss/postcss
- tailwindcss-animate wired via @plugin in globals.css
- prettier-plugin-tailwindcss bumped to 0.7.3 (Tailwind 4 compatible)
- Fix two Badge variant prop literals that the codemod incorrectly
  rewrote to 'outline-solid' in src/app/(app)/admin/page.tsx; Badge
  variant is still 'outline'

Co-authored-by: Rishi Desai <RishiDesai@users.noreply.github.com>

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>

Author: RishiDesai

frontend/next-env.d.ts

@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-/// <reference path="./.next/types/routes.d.ts" />
+import "./.next/types/routes.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.

frontend/package.json

@@ -11,9 +11,12 @@
     "format": "prettier --write \"src/**/*.{ts,tsx,js,jsx,json,css,md}\"",
     "format:check": "prettier --check \"src/**/*.{ts,tsx,js,jsx,json,css,md}\""
   },
-  "//": "All dependencies pinned to exact versions for supply-chain security. Upgrade via `pnpm up <pkg>@<version>` and commit the regenerated pnpm-lock.yaml. CI + Dockerfile use `pnpm install --frozen-lockfile` to reject drift.",
+  "//": [
+    "All dependencies pinned to exact versions for supply-chain security. Upgrade via `pnpm up <pkg>@<version>` and commit the regenerated pnpm-lock.yaml. CI + Dockerfile use `pnpm install --frozen-lockfile` to reject drift.",
+    "ESLint 10 deferred until eslint-plugin-react releases an eslint@10-compatible version."
+  ],
   "dependencies": {
-    "@clerk/nextjs": "6.36.8",
+    "@clerk/nextjs": "7.2.5",
     "@lobehub/icons": "5.5.4",
     "@radix-ui/react-accordion": "1.2.12",
     "@radix-ui/react-alert-dialog": "1.1.15",
@@ -30,7 +33,7 @@
     "@tanstack/react-virtual": "3.13.24",
     "class-variance-authority": "0.7.1",
     "clsx": "2.1.1",
-    "lucide-react": "0.468.0",
+    "lucide-react": "1.9.0",
     "mammoth": "1.12.0",
     "next": "16.2.4",
     "prism-react-renderer": "2.4.1",
@@ -48,17 +51,17 @@
   },
   "devDependencies": {
     "@eslint/js": "9.39.2",
+    "@tailwindcss/postcss": "4.2.4",
     "@types/node": "22.19.5",
     "@types/react": "19.2.14",
     "@types/react-dom": "19.2.3",
-    "autoprefixer": "10.5.0",
     "eslint": "9.39.2",
     "eslint-plugin-react": "7.37.5",
     "eslint-plugin-react-hooks": "7.1.1",
     "postcss": "8.5.10",
     "prettier": "3.8.3",
-    "prettier-plugin-tailwindcss": "0.6.14",
-    "tailwindcss": "3.4.19",
+    "prettier-plugin-tailwindcss": "0.7.3",
+    "tailwindcss": "4.2.4",
     "typescript": "6.0.3",
     "typescript-eslint": "8.59.0"
   }