chore: update gitignore to exclude Next.js build artifacts and certificates

- Add web/.next and web/out to ignore list
- Exclude backend/certbot and *.pem files
- Prevents build artifacts from being tracked

.gitignore

@@ -7,6 +7,15 @@ build/
 .cache/
 .env*
 
+# Next.js
+web/.next/
+web/out/
+web/.cache/
+
+# Build artifacts
+backend/certbot/
+*.pem
+
 # Mobile/Flutter/Expo (if chosen later)
 .gradle/
 android/app/build/