chore: drop next-intl dependency and orphaned routing config

Follow-up to the middleware fix: next-intl is no longer referenced
anywhere in the app (the only two references, src/middleware.ts and
src/i18n/routing.ts, were removed/emptied in the previous commit).
Removed the dependency from package.json and deleted the now-dead
src/i18n/routing.ts, and regenerated pnpm-lock.yaml (pnpm install)
to match.

Author: praizehimm

package.json

@@ -35,7 +35,6 @@
     "@tanstack/react-query": "^5.60.5",
     "framer-motion": "^11.11.17",
     "next": "15.5.24",
-    "next-intl": "^4.13.7",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
     "recharts": "^3.9.0",