quak files takes the collection ID as an optional argument (closes #211)

Mandatory arguments are positional, so `quak files` takes the collection
ID as an optional argument and the `--collection` option is removed.
With a collection ID it lists that collection's files. Without one it
lists every file in the account, collection by collection, each file
once: the library keeps a record of a file for each collection that
holds it, and only the first collection's record is listed, so that
collection is its `collectionID` in `--json`. The `--help` text, the
README and `TODO.md` say so.

Model: opus-5-5

TODO.md

@@ -17,8 +17,7 @@ pre-1.0
 
 # Next Step
 
-No bug is open. Two changes sneak asked for are open:
-https://git.eeqj.de/sneak/quak/issues/211 and
+No bug is open. One change sneak asked for is open:
 https://git.eeqj.de/sneak/quak/issues/212. The check of quak against a live Ente
 account, https://git.eeqj.de/sneak/quak/issues/187, needs an account only sneak
 has, so it waits on him.
@@ -28,6 +27,13 @@ declares one.
 
 # Completed Steps
 
+- 2026-10-18: `quak files` takes the collection ID as an optional argument
+  instead of the `--collection` option, which is gone
+  (https://git.eeqj.de/sneak/quak/issues/211). With no argument it lists every
+  file in the account once, collection by collection; a file in several
+  collections is listed with the first of them, which is its `collectionID` in
+  `--json`. The fresh read in `src/cli-read.ts` does this.
+
 - 2026-10-18: Names quak builds from an album name or a title fit in a file name
   (https://git.eeqj.de/sneak/quak/issues/205). `shortenKeepingExtension` in
   `src/filename.ts` cuts a name short to a number of bytes, keeping its