Delete several objects from the bucket

Deletes the selected objects, backing the "Delete selected" bulk action in the object browser. Same rules as storage.bucket.object.delete, applied to a selection of up to 1000 keys: every key is validated BEFORE anything is deleted, so an unknown key fails the whole request and no object is removed. Duplicate keys in the selection are deleted once. Validation: bucketId must reference an existing, non-deleted bucket in the scope (unknown → 404 NOT_FOUND); keys must hold 1–1000 non-empty object keys, none a folder prefix (→ 422 VALIDATION_FAILED); every key must be in the bucket's object inventory (otherwise → 404 NOT_FOUND with details.missingKeys, nothing deleted); a bucket that is creating, deleting or in error cannot be written (→ 409 CONFLICT); a legacy delete-protected bucket (objectLock: true) refuses object deletion on this API and the console (→ 409 LOCKED; direct OpenStack Swift access is not restricted); caller must hold owner|admin|contributor on the scope, otherwise 403 FORBIDDEN. Async & state: Synchronous — returns 200 with the BucketObjectsDeleteResult (the deleted keys and the recomputed counters). If the provider fails part-way, the inventory is left untouched and nothing is recorded against the Idempotency-Key; the provider delete is idempotent, so retrying the same request converges. Errors: 401 unauthenticated; 403 caller lacks write permission on the scope; 404 unknown scopeId, bucketId or any selected key; 409 CONFLICT bucket state does not permit the write; 409 LOCKED the bucket has object lock; 422 invalid selection; 503 object store unavailable; 500 unexpected backend failure. Idempotency/Concurrency: Idempotency-Key is optional; replaying the same key and body returns the original 200 result without a second delete; the same key with a different selection → 409 CONFLICT.