build: migrate from npm to pnpm with workspace catalogs

- Switch package manager to pnpm 10 via corepack
- Add pnpm-workspace.yaml with 54+ shared dependency catalogs
- Convert all workspace packages to catalog: and workspace:* protocols
- Upgrade Turborepo from 1.x to 2.8.12 (pipeline -> tasks)
- Upgrade apps/openpage-api from Next 15 to Next 16
- Update Docker, CI workflows, and GitHub Actions for pnpm
- Convert patch file to pnpm native format
- Replace deprecated next lint with standalone eslint
- Update all documentation references from npm to pnpm
- Fix stale dependabot config and documentation paths

apps/openpage-api/package.json

@@ -6,17 +6,17 @@
     "dev": "next dev -p 3003",
     "build": "next build",
     "start": "next start -p 3003",
-    "lint:fix": "next lint --fix",
+    "lint:fix": "eslint . --fix",
     "clean": "rimraf .next && rimraf node_modules"
   },
   "dependencies": {
-    "@documenso/prisma": "*",
-    "luxon": "^3.7.2",
-    "next": "15.5.12"
+    "@documenso/prisma": "workspace:*",
+    "luxon": "catalog:",
+    "next": "16.1.6"
   },
   "devDependencies": {
-    "@types/node": "^20",
-    "@types/react": "18.3.27",
-    "typescript": "5.6.2"
+    "@types/node": "catalog:",
+    "@types/react": "catalog:",
+    "typescript": "catalog:"
   }
 }