feat(contracts,server,web): files G6–G8 fields and identify S-7 contract

- G6: FileRoot.pendingCount/pendingPartial for download roots (same rule as the
  unidentified filter, recursive, cached 5 min, invalidated by files.changed)
- G7: FileEntry.parsedHint from parseReleasePath (file + parent dirs); the web
  subline uses it and no longer parses names itself
- G8: FileIdentifyCandidate.posterUrl (TMDB poster_path via adapter and
  catalog.lookup, local entities from metadata.posterPath); thumbnails in the
  identify panel
- S-7 contract: FilesIdentifyResult.remoteTaskId/remotePending,
  MediaServerInventory.partial, EventType identify.completed with
  IdentifyCompletedPayload; identify panel (useIdentifyLive) and organize wizard
  merge remote results by root + path, buffering events that beat the response

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

packages/contracts/src/organization.ts

@@ -450,6 +450,8 @@ export const MediaServerInventory = z.object({
       observedAt: Timestamp,
     }),
   ),
+  /** 至少一个实例因查询失败 / 超时为 unknown(没有外部 ID 不算);旧服务端不返回 */
+  partial: z.boolean().optional(),
 });
 export type MediaServerInventory = z.infer<typeof MediaServerInventory>;