Add per-user library settings, folder passwords, and a still picker.

Settings manages folders, thumbnail defaults, and passwords for the signed-in account, and choosing an image now browses saved stills instead of only the desktop file dialog.

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

server/api/library/clips/[id].delete.ts

@@ -1,6 +1,8 @@
 export default defineEventHandler(async (event) => {
-  assertLibraryAccess(event)
-  const id = getRouterParam(event, 'id')
-  await deleteClip(String(id))
+  const { owner } = assertLibraryOwner(event)
+  const id = String(getRouterParam(event, 'id') || '')
+  const clip = getClip(owner, id)
+  assertFolderAccess(event, clip.folderId)
+  await deleteClip(owner, id)
   return { ok: true }
 })