style(portal-bff): apply prettier to check-database-url.ts

Cosmetic-only — collapses one over-cautious multi-line
`throw new Error(...)` into a single line that fits within the
project's 100-char `printWidth`.

The reformat was produced by lint-staged DURING the amend that
landed #70, but applied to the working tree only — the modification
never made it back into the staged content of the amend, so the
merged commit has the un-prettified version. Spotted because
`pnpm exec prettier --check` fails locally; left unchecked, this
would break the next PR's `check` job at `format:check`.

No behavioural change.

apps/portal-bff/src/config/check-database-url.ts

@@ -34,9 +34,7 @@ export function assertDatabaseUrl(): void {
   }
 
   if (parsed.protocol !== 'postgresql:' && parsed.protocol !== 'postgres:') {
-    throw new Error(
+    throw new Error(`DATABASE_URL must use the "postgresql://" scheme; got "${parsed.protocol}".`);
-      `DATABASE_URL must use the "postgresql://" scheme; got "${parsed.protocol}".`,
-    );
   }
 
   // Heuristic — multiple "@" before the path almost always means the