fix(#411): resolve CI lint errors — prettier, unused directives, no-base-to-string

- auth.config.ts: collapse multiline template literal to single line
- auth.controller.ts: add eslint-disable for intentional no-unnecessary-condition
- auth.service.ts: remove 5 unused eslint-disable directives (Node 24 resolves
  BetterAuth types), fix prettier formatting, fix no-base-to-string
- login/page.tsx: remove unnecessary String() wrapper
- auth-context.test.tsx: fix prettier line length

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/api/src/auth/auth.config.ts

@@ -184,9 +184,7 @@ export function getTrustedOrigins(): string[] {
         origins.push(origin);
       } catch (urlError: unknown) {
         const detail = urlError instanceof Error ? urlError.message : String(urlError);
-        console.warn(
-          `[AUTH] Ignoring invalid URL in TRUSTED_ORIGINS: "${origin}" (${detail})`
-        );
+        console.warn(`[AUTH] Ignoring invalid URL in TRUSTED_ORIGINS: "${origin}" (${detail})`);
       }
     }
   }