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

src/library/index.ts

@@ -20,9 +20,10 @@
 //
 // `freshCollections()` is the fresh read of the collection list alone (issue
 // #210): one collections request, no collection's files, and nothing stored,
-// for a caller such as `quak collections` that needs no more. A caller that
-// asks for each refresh it needs can also open the library with
-// `refreshOnOpen: false`, so that `open()` starts none.
+// for a caller such as `quak collections` that needs no more. `freshFiles()`
+// is the fresh read of one collection's files, and stores nothing either
+// (issue #217). A caller that asks for each refresh it needs can also open the
+// library with `refreshOnOpen: false`, so that `open()` starts none.
 //
 // A refresh reports through `onProgress` each collection whose files it has
 // fetched, so a large account, whose first refresh fetches the files of every
@@ -625,6 +626,24 @@ export class Library {
         return collections;
     }
 
+    // The fresh read of one collection's files (issue #217): every live file
+    // in it that decrypts, in the server's order. `collection` is a record
+    // `freshCollections()` returned, whose key decrypts the files. It fetches
+    // no other collection's files. Like `freshCollections()`, it stores
+    // nothing. It returns each file once, as the latest copy the server sent,
+    // where the first copy was.
+    async freshFiles(collection: Collection): Promise<EnteFile[]> {
+        if (this.closed) throw new Error("the library is closed");
+        const { files } = await this.client.filesSince({
+            collectionID: collection.id,
+            collectionKey: collection.key,
+            sinceTime: 0,
+        });
+        const byID = new Map<number, EnteFile>();
+        for (const file of files) byID.set(file.id, file);
+        return [...byID.values()];
+    }
+
     // Back up every in-scope file to `opts.downloadDirectory`, or else the
     // library's, each original at its save path, with a durable failure
     // ledger (issue #51). Takes the lock in that directory first, unless the