Add paginated library JSON and dedicated still thumbs that never stream archive masters.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/api/library/stills/[id]/thumb.get.ts

@@ -0,0 +1,26 @@
+import { existsSync, createReadStream } from 'node:fs'
+import { fileEtag, stillPath, stillThumbPath } from '~/server/utils/library'
+
+export default defineEventHandler(async (event) => {
+  const { owner } = assertLibraryOwner(event)
+  const id = String(getRouterParam(event, 'id') || '')
+  const still = getStill(owner, id)
+  assertFolderAccess(event, still.folderId)
+
+  const path = await stillThumbPath(owner, id)
+  const original = stillPath(owner, still.id)
+  // Never stream the archive master as a "thumb"
+  if (!path || !existsSync(path) || path === original) {
+    throw createError({ statusCode: 404, statusMessage: 'Thumbnail not found' })
+  }
+
+  const etag = fileEtag(path)
+  setHeader(event, 'ETag', etag)
+  setHeader(event, 'Cache-Control', 'public, max-age=86400')
+  if (getHeader(event, 'if-none-match') === etag) {
+    setResponseStatus(event, 304)
+    return null
+  }
+  setHeader(event, 'Content-Type', 'image/jpeg')
+  return sendStream(event, createReadStream(path))
+})