import: the whole feature, and releases put back together

Everything the import grew over the last week, landing in one go — the
window, the picker, the audition pen, apply, and the review that stands
between them.

The fold is the new part. A release filed as a container of parts arrived
as N albums, because the scan groups audio by its immediate parent and the
container holds none of its own: Analord's eleven volumes were eleven
records, and six more releases split the same way. Records now fold into
the release above them, and apply is handed an explicit part list — never a
recursive walk, which is what let one stray file swallow 288 descendants
and duplicate 9 GB.

Where releases live is read off the collection rather than assumed, so a
genre-nested library moves the answer instead of breaking; below a dominant
majority at one depth the pass refuses entirely, because no folding beats
wrong folding. Three vetoes independent of depth catch a misread level.
Every fold is listed in the review with a way out.

research/import/fold-audit.mjs imports the shipping module, so the audited
code is the running code: 9 folds, 0 swallows across four library shapes,
and none of the 148 artist folders touched. It was that harness that killed
the tempting version of this rule — matching a part against its container
folded 40 artist folders, Mac Demarco's 8 albums into one, because album
folders carry the artist's name.

The regression test found a live bug on the way: parts number from 01 each,
so flattening two discs collided, and "same name, same size" read the
second file as already-imported and dropped it while still counting it.
That reuse now also requires that this run has not already written the
path.

Also here: the picker's accent crossfades between records instead of
cutting through the app's blue (ownership moved to the window, which
survives the per-record re-key), the fullscreen viewer wears the album's
accent instead of the one it left behind in the portal, Skip defers a
record without deciding it, and Keep mine is gone — with the cards picked
field by field it was Next under another name.

crates/soulseek-client/src/lib.rs

@@ -379,13 +379,29 @@ impl Client {
     /// Start downloading `filename` (full remote path) from `username`.
     /// Progress streams out as [`Event::Download`]. Returns the download id.
     pub fn download(&self, username: &str, filename: &str, size: u64) -> u64 {
-        transfer::start_download(self.inner.clone(), username, filename, size, None)
+        transfer::start_download(self.inner.clone(), username, filename, size, None, |_| {})
     }
 
     /// Like [`download`](Self::download) but writing to an explicit local
     /// path (used for stream-to-cache).
     pub fn download_to(&self, username: &str, filename: &str, size: u64, target: PathBuf) -> u64 {
-        transfer::start_download(self.inner.clone(), username, filename, size, Some(target))
+        transfer::start_download(self.inner.clone(), username, filename, size, Some(target), |_| {})
+    }
+
+    /// `download_to`, with `claim` run on the new id BEFORE the transfer task
+    /// is spawned. A download emits `Connecting` the instant it starts, so a
+    /// caller that must recognise its own transfers — the import tool's
+    /// audition pen — has to be able to register the id first. Doing it on the
+    /// returned value is a race the emitter usually wins.
+    pub fn download_to_claimed(
+        &self,
+        username: &str,
+        filename: &str,
+        size: u64,
+        target: PathBuf,
+        claim: impl FnOnce(u64),
+    ) -> u64 {
+        transfer::start_download(self.inner.clone(), username, filename, size, Some(target), claim)
     }
 
     /// Cancel an active download by id.