Add migration for User.country column

The country field was in the schema but missing its migration.
This was causing user.get and user.me queries to fail.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

prisma/migrations/20260205200000_add_user_country/migration.sql

@@ -0,0 +1,12 @@
+-- Add country column to User table
+-- This is used for mentor matching and geographic filtering
+
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_name = 'User' AND column_name = 'country'
+    ) THEN
+        ALTER TABLE "User" ADD COLUMN "country" TEXT;
+    END IF;
+END $$;