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.

src/lib/api.js

@@ -223,6 +223,36 @@ export const playerFadePauseAcked = (fadeMs) =>
 export const playerFadeResume = (fadeMs) =>
     invoke("player_fade_resume", { fadeMs });
 export const debugStats = () => invoke("debug_stats");
+
+// ---- the import tool (see src-tauri/src/import.rs) ------------------------
+// Scan is read-only; apply COPIES into the managed root and registers — the
+// source folder is never written to.
+export const importScan = (root) => invoke("import_scan", { root });
+export const importSessionGet = () => invoke("import_session_get");
+export const importSessionSet = (state) => invoke("import_session_set", { state });
+export const importSessionClear = () => invoke("import_session_clear");
+export const importGetDest = () => invoke("import_get_dest");
+export const importSetDest = (dir, layout = null) => invoke("import_set_dest", { dir, layout });
+export const importApply = (sourceRoot, albums) => invoke("import_apply", { sourceRoot, albums });
+// On-demand per-record identification (Deezer try-list → MB fallback) and
+// the artwork panel's cover report. Both read-only.
+export const importIdentify = (artist, title) => invoke("import_identify", { artist, title });
+export const importCoverReport = (artist, title, referenceUrl) =>
+    invoke("import_cover_report", { artist, title, referenceUrl });
+// The record's own artwork, measured (embedded first, else folder images).
+export const importLocalArt = (sourceRoot, rel) => invoke("import_local_art", { sourceRoot, rel });
+// Prune rows whose files are gone, then index anything new — the real rescan.
+export const rescanLibrary = () => invoke("rescan_library");
+// Download a found album copy into (Cache)\_audition\<rel>\ for the version
+// comparison. files ordered track-1-first; returns transfer ids.
+export const importAudition = (username, rel, files) =>
+    invoke("import_audition", { username, rel, files });
+export const onImportAudition = (cb) => listen("import:audition", (e) => cb(e.payload));
+// Measured facts about one audio file (the version card's quality chips).
+export const importProbeFile = (path) => invoke("import_probe_file", { path });
+export const onImportScan = (cb) => listen("import:scan", (e) => cb(e.payload));
+export const onImportScanFolder = (cb) => listen("import:scan-folder", (e) => cb(e.payload));
+export const onImportApply = (cb) => listen("import:apply", (e) => cb(e.payload));
 export const previewControl = (action, value = null) =>
     invoke("preview_control", { action, value });
 export const previewDispose = () => invoke("preview_dispose");