feat(now-playing): OpenSubsonic playbackReport for live now-playing (#1080)

* feat(now-playing): adopt OpenSubsonic playbackReport for live now-playing

Drive a small playback state machine (starting → playing ↔ paused → stopped)
on the Subsonic-server channel when the server advertises the OpenSubsonic
`playbackReport` extension (Navidrome ≥ 0.62), giving `getNowPlaying` a real
transport state and an extrapolated position. Reports send `ignoreScrobble=true`
so play counts stay on the existing `scrobble.view` 50% path (no double count),
and the effective playback speed is included so the server extrapolates position
correctly with the speed feature on.

- New `playbackReportSession` FSM mirrors the existing `playListenSession`
  lifecycle hooks and is wired at the same player call sites (start / gapless
  switch / queue restore / resume / 15s heartbeat / pause / seek / stop / ended /
  error / app quit). Servers without the extension degrade to the unchanged
  legacy `scrobble.view?submission=false` presence call.
- Gated through the existing serverCapabilities framework: a new
  `FEATURE_PLAYBACK_REPORT` (auto, extension-detected). The OpenSubsonic
  extensions probe now stores the full advertised list once and serves both
  AudioMuse `sonicSimilarity` and `playbackReport` from it, without disturbing
  the legacy Instant Mix opt-in on pre-0.62 servers.
- Now Playing dropdown shows a live position bar and a paused indicator.
- reportPlayback uses the real request params (mediaId / mediaType / positionMs).

Tests: FSM transitions + gating + legacy fallback, capability resolution,
extension-list probe storage/decoupling. Full suite green; no Tauri-boundary
changes.

* feat(now-playing): glide the Live position bar between polls

Extrapolate the position of `playing` entries locally (elapsed × reported
playbackRate from the last 10 s poll) and re-render once a second, so the Live
progress bar advances smoothly instead of jumping on each refresh. Paused and
position-less entries stay frozen. A linear width transition matched to the tick
keeps the fill gliding. Only applies to clients that report a position via the
playbackReport extension.

* fix(now-playing): tighten Live timer layout and report resume immediately

Keep the progress-bar width stable without a wide empty gap before the
timer: reserve ~2ch inside the current-time span only (right-aligned), not
on the whole clock block. Report `playing` to the server as soon as
resume() runs, matching the immediate `paused` report on pause instead of
waiting for the Rust `audio:playing` event.

* docs: CHANGELOG and credits for playbackReport live now-playing (PR #1080)

src/serverCapabilities/resolve.test.ts

@@ -2,7 +2,9 @@ import { describe, expect, it } from 'vitest';
 import { buildCapabilityContext } from './context';
 import {
   FEATURE_AUDIOMUSE_SIMILAR_TRACKS,
+  FEATURE_PLAYBACK_REPORT,
   OP_SIMILAR_TRACKS,
+  PLAYBACK_REPORT_EXTENSION,
   PROBE_LEGACY_INSTANT_MIX,
   PROBE_OPENSUBSONIC_EXTENSIONS,
   SERVER_CAPABILITY_CATALOG,
@@ -50,10 +52,40 @@ describe('neededProbeIds', () => {
     expect(ids.has(PROBE_OPENSUBSONIC_EXTENSIONS)).toBe(true);
     expect(ids.has(PROBE_LEGACY_INSTANT_MIX)).toBe(false);
   });
-  it('asks for the legacy probe on 0.61', () => {
+  it('asks for the legacy probe on 0.61, plus the extensions probe for playbackReport', () => {
     const ids = neededProbeIds(SERVER_CAPABILITY_CATALOG, ctxFor('0.61.0'));
     expect(ids.has(PROBE_LEGACY_INSTANT_MIX)).toBe(true);
-    expect(ids.has(PROBE_OPENSUBSONIC_EXTENSIONS)).toBe(false);
+    // playbackReport detection is OpenSubsonic-generic, so the extensions probe
+    // is now needed on any OpenSubsonic server (the fetch is shared).
+    expect(ids.has(PROBE_OPENSUBSONIC_EXTENSIONS)).toBe(true);
+  });
+});
+
+describe('playbackReport capability', () => {
+  const pbDef = getCapabilityDefinition(FEATURE_PLAYBACK_REPORT)!;
+  const withExt: ProbeOutcome = { status: 'present', extensions: [PLAYBACK_REPORT_EXTENSION] };
+  const withoutExt: ProbeOutcome = { status: 'present', extensions: [SONIC_SIMILARITY_EXTENSION] };
+
+  it('is auto-active on any OpenSubsonic server that advertises the extension', () => {
+    const r = resolveCapability(pbDef, ctxFor('0.62.0'), { [PROBE_OPENSUBSONIC_EXTENSIONS]: withExt });
+    expect(r).toMatchObject({ status: 'present', activation: 'auto', trust: 'high' });
+    expect(isCapabilityActive(r, false)).toBe(true);
+  });
+
+  it('detects on non-Navidrome OpenSubsonic servers too', () => {
+    const r = resolveCapability(pbDef, ctxFor('1.16.1', 'gonic'), { [PROBE_OPENSUBSONIC_EXTENSIONS]: withExt });
+    expect(r.status).toBe('present');
+  });
+
+  it('is absent when the extension is not advertised', () => {
+    const r = resolveCapability(pbDef, ctxFor('0.62.0'), { [PROBE_OPENSUBSONIC_EXTENSIONS]: withoutExt });
+    expect(r.status).toBe('absent');
+    expect(isCapabilityActive(r, true)).toBe(false);
+  });
+
+  it('is ineligible on non-OpenSubsonic servers', () => {
+    const r = resolveCapability(pbDef, buildCapabilityContext({ type: 'subsonic', serverVersion: '1.16.1', openSubsonic: false }), {});
+    expect(r.status).toBe('ineligible');
   });
 });