M2c-dev: development compose stack, backup job, Firebase setup docs

infra/dev: compose stack on the Mac (server kvitt-server:dev, on-demand backup),
.env.example, build/up/logs/backup/copy-google-services scripts. No Caddy, no TLS
(debug builds accept http to private LAN addresses, AC-2.8). Bind-mounted data.
infra/backup: alpine 3.24.2 image and backup.sh (SPEC 10.9; Drive upload skipped
when RCLONE_FOLDER_ID is empty). infra/README.md for the dev stack and Firebase.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

@@ -27,3 +27,10 @@ infra/secrets/
 *service-account*.json
 google-services.json
 *.apk
+# Development stack on the Mac (infra/dev): local env, bind-mounted data and local backups
+infra/dev/.env
+infra/dev/data/
+infra/dev/backups/
+*.sqlite.gz
+*.sqlite-wal
+*.sqlite-shm