fix(v3): decode stats:recorded filename so post-play score badge refreshes (#620)

PR #574 added a `stats:recorded` -> in-place accuracy-badge repaint so a
just-earned score shows without restarting the app. But the repaint never
matched a card, so the badge stayed stale until a full render() (app
restart / search / re-enter the screen) -- exactly the "only updates after
a restart" report.

Root cause is a filename key-space mismatch. The event (like song:loading)
carries the filename `encodeURIComponent`'d, because that is what playCard
hands to playSong (the highway WS decodeURIComponent's it). Library cards,
though, key on the DECODED localFilename (data-fn), and /api/stats/best is
server-canonicalized to that same decoded key (server.py
_canonical_song_filename). So repaintAccuracy's `data-fn !== key` check
rejected every card and `state.accuracy[encoded]` was undefined.

Decode the event filename back into the card / state.accuracy key space via
a small `decFn` helper before marking dirty and repainting, fixing both the
immediate repaint and the onV3SongsScreenEnter deferred path. decFn is
idempotent for already-decoded names and falls back to the original on
malformed input, so a real filename containing a literal '%' is never
corrupted.

Tests: tests/js/v3_songs_score_badge_refresh.test.js extracts the real
decFn from the shipped source and proves the encoded event filename
round-trips to the raw card key (incl. spaces and subfolder '/').


Claude-Session: https://claude.ai/code/session_01QbexxfTt8q2tAn436MqGWF

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: byrongamatos <xasiklas@gmail.com>

static/v3/songs.js

@@ -15,6 +15,20 @@
     const esc = (s) => String(s == null ? '' : s).replace(/[&<>"']/g, (c) => (
         { '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' }[c]));
     const enc = encodeURIComponent;
+    // Inverse of `enc` for matching a played song's filename back to a library
+    // card. The `stats:recorded` event (like `song:loading`) carries the
+    // filename exactly as it was handed to `playSong` — i.e. encodeURIComponent'd
+    // (see `playCard`, and the highway WS which decodeURIComponent's it). But
+    // cards key on the DECODED library filename (`cardKey` → `localFilename`),
+    // and `/api/stats/best` is server-canonicalized to that same decoded key, so
+    // an encoded filename matches no card and the post-play badge repaint silently
+    // no-ops. Decode to land in the card/`state.accuracy` key space. Idempotent
+    // for already-decoded names (no '%'); on malformed input falls back to the
+    // original so a real filename containing a literal '%' is never corrupted.
+    function decFn(fn) {
+        if (typeof fn !== 'string' || fn.indexOf('%') === -1) return fn || '';
+        try { return decodeURIComponent(fn); } catch (_) { return fn; }
+    }
 
     const SORTS = [
         ['artist', 'Artist A–Z'], ['artist-desc', 'Artist Z–A'],
@@ -1173,7 +1187,13 @@
         // If the library is visible right now, repaint immediately; otherwise
         // mark it dirty and onV3SongsScreenEnter applies it on return.
         sm.on('stats:recorded', (e) => {
-            const fn = e && e.detail && e.detail.filename;
+            // Decode to the library-card key space — the event carries the
+            // encodeURIComponent'd filename, but cards (data-fn) and
+            // state.accuracy key on the decoded library filename. Without this
+            // the repaint below (and applyScoreRefresh's repaintAccuracy) match
+            // no card, so a just-earned score stays invisible until a full
+            // render() (restart / search / re-enter), which is this bug.
+            const fn = decFn(e && e.detail && e.detail.filename);
             if (!fn) return;
             _dirtyScores.add(fn);
             // Only repaint now if the library is the active screen; otherwise