fix(files,security): S-1 per-source Move authorization, S-2 session-only annotation, S-5 restore guards

S-1 (/files/move, /files/organize action=move):
- organize-guard: authorizeMoveEntities checks every source's media entities
  (declared entity plus entities of registered assets under the source);
  one-time approval still covers the whole request; any source that cannot
  be attributed to an entity only passes with an approval; denial lists every
  unauthorized item; optional non-consuming pre-check
- transfer: entities per source (directory = registered assets beneath it)
- organize: all move groups pre-checked before any group executes; any
  denial -> whole request 403 approval_required
S-2:
- api.ts: GET /files/download and POST /files/trash/purge marked
  auth:"session"; files routes attach requireAdminSession from the registry
  annotation; handler-side purge check removed, download keeps a same-rule
  defense check; permanent delete uses isAdminSession
- DEV key rule written down: equals an admin-scope key for session-only
  endpoints, still admin for Move/delete approval bypass (as authorizeMove)
- api-registry.test: session list updated; new reverse assertion that no
  non-session endpoint answers 403 to an admin-scope bearer
S-5 (trash restore):
- restore-to requires a writable managed library root (isWritableTarget)
- in-place restore rebuilds missing parents level by level without
  following symlinks (mkdirWithin), realpath-checked per level
- cross-volume restore capped by FILES_TRASH_CROSS_MAX_BYTES; cross-volume
  copies (trash in / restore out) go through fsproxy
Tests: multi-entity move 403 + listing, unattributed source, organize foreign
asset 403, download/purge 403 for DEV and admin-scope keys, restore target
not writable, symlinked parent, rebuild parents, cross-volume cap.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/contracts/src/api.ts

@@ -1149,7 +1149,8 @@ export const Api = {
       method: "post",
       path: "/files/trash/purge",
       scope: "admin",
-      summary: "清空回收站(缺省只清过期项;服务端另要求 admin 控制台会话,API Key 403)",
+      auth: "session",
+      summary: "清空回收站(缺省只清过期项;仅管理员控制台会话,API Key 与 DEV key 一律 403)",
       body: files.FilesTrashPurgeRequest,
       response: files.FilesTrashPurgeResult,
     }),
@@ -1181,7 +1182,8 @@ export const Api = {
       method: "get",
       path: "/files/download",
       scope: "admin",
-      summary: "下载小文件(nfo/字幕/图片,≤20 MiB;流式;服务端另要求 admin 控制台会话;审计)",
+      auth: "session",
+      summary: "下载小文件(nfo/字幕/图片,≤20 MiB;流式;仅管理员控制台会话;审计)",
       query: files.FilesDownloadQuery,
       response: files.FilesDownloadResponse,
     }),