fix(auth): revert lint autofix that broke hasExternalApiCredentials return type

Biome auto-fixed `return auth !== null && auth.startsWith(...)` to
`return auth?.startsWith(...)` which returns `boolean | undefined`,
not `boolean`, causing a TypeScript build failure.

Author: waleedlatif1

apps/sim/lib/auth/hybrid.ts

@@ -25,7 +25,7 @@ const BEARER_PREFIX = 'Bearer '
 export function hasExternalApiCredentials(headers: Headers): boolean {
   if (headers.has(API_KEY_HEADER)) return true
   const auth = headers.get('authorization')
-  return auth?.startsWith(BEARER_PREFIX)
+  return auth !== null && auth.startsWith(BEARER_PREFIX)
 }
 
 export interface AuthResult {