quak files COLLECTION fetches that collection's files alone (closes #217)

`quak files` with a collection ID used to wait for a full refresh, which
on an empty cache fetched the files of every collection in the account.
It now reads the collection list, then that one collection's files
through the new `Library.freshFiles()`, and stores nothing. The files
print in the server's order, and no refresh progress lines appear. Each
file prints once, as the latest copy the server sent. `quak files`
without a collection ID still waits for a refresh.

Some tests ran `quak files` with a collection ID to fill the cache, to
show a refresh's progress or to show what `-q` hides. They now run a
command that still refreshes.

Model: opus-5-5

TODO.md

@@ -26,6 +26,13 @@ declares one.
 
 # Completed Steps
 
+- 2026-10-26: `quak files` with a collection ID fetches that collection's files
+  alone (https://git.eeqj.de/sneak/quak/issues/217). It used to wait for a
+  refresh, which on an empty cache fetched the files of every collection. It now
+  reads the collection list through `lib.freshCollections()`, then the one
+  collection's files through the new `lib.freshFiles()`. It stores nothing, and
+  the files print in the server's order.
+
 - 2026-10-22: The JSON `quak backup` and `quak backup-metadata` write for a file
   holds `keywords` in place of the CLIP embedding in its ML data
   (https://git.eeqj.de/sneak/quak/issues/218). The keywords are the titles of