fix(web): pin Next SWC binaries and regenerate lockfile with CI's npm

Since the SDK 56 dependency churn, arborist nests next under apps/web and
npm 10 skipped its platform-optional SWC binaries on the x64 CI runner,
breaking next build. Pin the linux and darwin binaries as direct
optionalDependencies of @sauci/web (bump alongside next) and regenerate
the lockfile from scratch with npm 10.8.2 to match CI. Verified in a
linux/amd64 node:20.19.4 container: npm ci installs the binary.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/web/package.json

@@ -28,5 +28,10 @@
     "postcss": "^8.4.0",
     "tailwindcss": "^3.4.0",
     "typescript": "^5.3.0"
+  },
+  "optionalDependencies": {
+    "@next/swc-linux-x64-gnu": "15.5.24",
+    "@next/swc-linux-x64-musl": "15.5.24",
+    "@next/swc-darwin-arm64": "15.5.24"
   }
 }