Confirmed live against the real backend: docs/IM-前后端对接文档.md's flat
`/media` items ({thumbnail_file_id,file_id,width,height}) and flat search
hits ({file:{...}}, {url,title,...}) don't match what the server actually
returns. Both endpoints really return the raw original message (`{txt,fmt,
ent}`, search hits wrapped one level deeper in `snapshot`) -- the same shape
lib/messages/drafty.tsx's renderDrafty already knows how to render, reused
here instead of hand-picking fields from a shape that doesn't exist. This is
also why image/video thumbnails were rendering as generic icons: the field
they were reading was never present in a real response.
Extracted useAuthedBlobUrl (authenticated file-fetch-to-blob-URL) out of
AttachmentPreview into lib/hooks.ts so the history modal's own thumbnail
grid can reuse it instead of duplicating the fetch/header logic.
Also adds the URL safety-check gate (docs/IM-前后端对接文档.md:1822,1898)
before opening a link found via the 链接 tab, which this view didn't have
at all before.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
