fix: P0-5 — upload-status rollback, streaming copy (LOCAL only), user re-verify, honest lock

B1: `_mark_upload_failed_and_raise` now commits on a separate session
  - Helper takes `request + upload_id`, opens a fresh session from
    `request.app.state.session_factory` and commits there before raising.
  - Closes the named-lock connection-pool leak Codex flagged: the old
    "commit-on-the-same-session" implementation could return the
    GET_LOCK connection to the pool before the enclosing
    `finally: release_named_lock` ran, leaking `mp:<hash>` for up to
    `pool_recycle` and re-opening the same-key upload race.
  - Same helper now used by `create_server_object_payload`'s put-failure
    branch — two failure paths have identical semantics.

B2: streaming copy for soft-delete + restore (`get_stream() + put()`)
  - LOCAL backend: zero-copy (aiofiles stream write). OOM fixed.
  - S3 backend: still OOMs on multi-GB objects — `put()` materializes
    the async iter via `b"".join(chunks)`. Multipart `put` is a
    follow-up; do NOT claim "OOM fixed on production" since production
    defaults to S3.

C1: worker re-verifies `Users.status='active' AND is_deleted=0`
  - `_assert_user_active` called from `_execution_context` after
    resolving `triggered_by`; skips `SYSTEM_CRON_USER_ID`.
  - `USER_DISABLED` error_code goes into the `NODE_FINISHED_EVENT`
    outbox payload — `schedule_node_runs` has no `error_code` column,
    the row only carries the `message` text. Docstrings corrected to
    say so explicitly (previous docstring falsely promised row-level
    observability).

F1: honest browser-local file lock
  - `api.ts` `acquireFileLock/heartbeatFileLock/releaseFileLock/
    releaseFileLockOnUnload` are now no-ops with comments stating they
    never call the network.
  - `scriptWorkspaceStore` dropped `tickHeartbeats`; `tickCleanup`
    simplified to just clear cache.
  - `useEditSessionLifecycle` dropped its 15s heartbeat `setInterval`.
  - `ScriptWorkspace.tsx` renders `.local-lock-banner` info bar when
    `isEditing`. Two tabs may still silently last-write — banner is the
    only guard (acceptable disclosure-only tradeoff).

Dead code: deleted the duplicate `upload_bytes_to_session` in
`backend/src/backend/storage_api.py`. The `services.storage` import
is now the only source of the function; `create_upload_record`'s
docstring updated to point at `backend.resources`.

frontend/app/features/platform/ScriptWorkspace.tsx

@@ -478,6 +478,18 @@ export function ScriptWorkspace({
         )}
       </div>
 
+      {/* 本地编辑锁提示——只在非 Python 编辑时显示，
+          因为 Python 编辑走 pythonEditorBuffers，不走文件锁。
+          这个锁只在本浏览器当前 tab 内有效，不能阻止隐身模式 / 其它浏览器同时编辑。 */}
+      {isEditing && (
+        <div className="local-lock-banner">
+          <Icon name="info" size={14} />
+          <span>
+            本地编辑锁——关闭标签页、刷新页面或换浏览器后失效，不会阻止他人同时编辑。
+          </span>
+        </div>
+      )}
+
       {/* 编辑器画布区域 - 始终渲染，保证 iframe 不重新加载 */}
       <div className="editor-canvas-wrapper" style={{ position: 'relative', width: '100%', height: '100%', overflow: 'hidden' }}>
         {/* 只读模式内容 - 用 CSS 控制显示/隐藏 */}