feat(account): let users delete their account

DELETE /api/users/me with the password sets users.deleted_at, ends all logins and frees the Steam ID. A nightly job removes users flagged 30 days ago, Core first, and prunes Core orphans. Dry run by default.

src/main/resources/application.yml

@@ -59,6 +59,15 @@ app:
   public-url: ${APP_PUBLIC_URL:http://localhost:8080}
   # Where the user lands after the Steam link.
   frontend-url: ${APP_FRONTEND_URL:http://localhost:5173}
+  core:
+    # Core inside the Docker network, for the account cleanup calls.
+    internal-url: ${APP_CORE_INTERNAL_URL:http://localhost:8090}
+  account-cleanup:
+    cron: "0 15 4 * * *"
+    # How long a deleted account waits before the cleanup removes it for good.
+    retention: 30d
+    # Log only, delete nothing. See the Deployment README before flipping it.
+    dry-run: ${APP_ACCOUNT_CLEANUP_DRY_RUN:true}
 
 # Registration settings
 auth: