Delete a file share

Soft-deletes the selected file share from the file share detail page "Delete" action. Deletion tears down the share's mount targets, stops billing for provisioned capacity, and removes the share from the scoped list; per platform policy the row is soft-deleted (deleted_at set) and excluded from all subsequent reads. Deletion is refused while unresolved dependencies exist — active mount targets serving connected clients, snapshots pinned by retention rules, or a governance lock on the resource — and the blocker is reported to the caller. Validation: fileShareId must reference a live share in the scope (→ 404 NOT_FOUND otherwise); the share must not be mid-provisioning (status CREATING) — transitional-state deletes → 409 CONFLICT; dependency blockers (attached clients/mount targets in use, retained snapshots) → 409 DEPENDENCY_BLOCKED; a management/governance lock → 409 LOCKED. RBAC: owner|admin (destructive-action permission enforced). Async & state: Asynchronous; returns 202 with an Operation resource. The share transitions AVAILABLE → (deleting) → soft-deleted; progress and the final resource.deleted notification are emitted as resource.updated SSE frames with kind "storage.file_share" until the Operation reaches succeeded|failed. Errors: 401 unauthenticated; 403 missing destructive permission; 404 unknown scopeId or fileShareId; 409 DEPENDENCY_BLOCKED unresolved dependants; 409 LOCKED resource lock; 412 If-Match ETag mismatch; 500 unexpected failure. Idempotency/Concurrency: Idempotency-Key is optional, the same contract as the bucket delete and every other async operation-return delete; replaying the same key returns the original 202 Operation. If-Match with the current ETag guards against deleting a share that changed since it was last read (mismatch → 412 PRECONDITION_FAILED).