infra/dev: env_value defaults match compose, die helper, shared Gradle lock check; drop unused RCLONE_REMOTE and M2a leftovers; fix stale Pi compose path

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

infra/dev/compose.yaml

@@ -1,5 +1,5 @@
 # Kvitt development stack on the owner's Mac (SPEC §10 "Development first", D-001).
-# Not the Pi stack: that is infra/compose.yaml, built by M2c-pi.
+# Not the Pi stack: that is infra/pi/compose.yaml (D-103).
 #
 # No Caddy and no TLS here: debug builds accept http:// to private LAN addresses (AC-2.8), so the
 # server publishes its own port on the Mac. Release builds never talk to this stack.
@@ -72,9 +72,9 @@ services:
     mem_limit: 96m
     environment:
       TZ: Europe/Stockholm
-      # Empty on the dev stack: the Drive upload is skipped and the local files are kept (§10.9, D-001).
+      # Empty on the dev stack: the Drive upload is skipped and the local files are kept (§10.9, D-001), so
+      # backup.sh reads no other rclone setting here.
       RCLONE_FOLDER_ID: ""
-      RCLONE_REMOTE: ${RCLONE_REMOTE:-gdrive:}
     volumes:
       - ${KVITT_DEV_DATA_DIR:-./data}:/data
       - ${KVITT_DEV_BACKUP_DIR:-./backups}:/backups