clone/drop-database: forward admin URL's dbname as MAINTENANCE_DATABASE

DigitalOcean managed Postgres (and other managed services) don't expose
a `postgres` maintenance DB. The admin URL the consumer provides is
already proven to connect to *some* working DB (its path component), so
forward that as MAINTENANCE_DATABASE rather than relying on the
hardcoded `postgres` default in clone.sh / drop.sh.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jmschneider

.github/actions/clone-database/action.yml

@@ -185,6 +185,11 @@ runs:
                 printf 'PGUSER=%s\n' "$KP_DB_USER"
                 printf 'PGPASSWORD=%s\n' "$KP_DB_PASSWORD"
                 [ -n "${KP_DB_SSLMODE:-}" ] && printf 'PGSSLMODE=%s\n' "$KP_DB_SSLMODE"
+                # Use the dbname from the admin URL as the maintenance DB.
+                # Managed services (e.g. DigitalOcean = `defaultdb`) often
+                # don't expose a `postgres` DB at all, but the admin URL is
+                # already proven to connect to *some* working DB.
+                [ -n "${KP_DB_DBNAME:-}" ] && printf 'MAINTENANCE_DATABASE=%s\n' "$KP_DB_DBNAME"
                 printf 'SOURCE_DATABASE=%s\n' "$src"
                 printf 'TARGET_DATABASE=%s\n' "$tgt"
               } > "$local_env"

.github/actions/drop-database/action.yml

@@ -148,6 +148,8 @@ runs:
                 printf 'PGUSER=%s\n' "$KP_DB_USER"
                 printf 'PGPASSWORD=%s\n' "$KP_DB_PASSWORD"
                 [ -n "${KP_DB_SSLMODE:-}" ] && printf 'PGSSLMODE=%s\n' "$KP_DB_SSLMODE"
+                # See clone action for why we forward the admin URL's dbname.
+                [ -n "${KP_DB_DBNAME:-}" ] && printf 'MAINTENANCE_DATABASE=%s\n' "$KP_DB_DBNAME"
                 printf 'TARGET_DATABASE=%s\n' "$tgt"
               } > "$local_env"
               ;;