fix(distributed): harden staged resource ownership

Bind cleanup to storage namespaces and generation-scoped quantization state. Validate backend outputs, prove inputs reach worker staging, and make failed-start cleanup retryable.

Assisted-by: Codex:GPT-5 [apply_patch] [exec_command]
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f