feat: v1.29.0 — Radio fast-start, seek fix, OGG, error toasts, contributors

Incorporates PRs #38 (nisarg-78), #42 #43 #44 (JulianNymark) with fixes:

Audio / Playback
- Artist Radio starts immediately from fast getTopSongs (local library);
  getSimilarSongs2 (Last.fm) enriches queue in background — no more wait
- Fix seek audio glitch: EqualPowerFadeIn only resets to zero-gain on
  seeks to track start (<100 ms); all other seeks resume at unity gain
- OGG/Vorbis container support via symphonia-format-ogg (PR #42)
- Human-readable audio error messages in SizedDecoder (PR #44)
- Audio playback errors shown as themed toast notifications (PR #43)

Queue / Radio
- Infinite Queue: proactive load of 5 tracks (was 25) when ≤2 remain
- Radio: proactive reload at ≤2 remaining tracks, independent of
  Infinite Queue setting — radio no longer stops at last track
- Fix: clicking Start Radio multiple times no longer stacks duplicates
- Fix: Start Radio on artist keeps current song playing
- Manual tracks always appear before Radio, Radio before Auto-added
- Queue separators: "— Radio —" and "— Auto —" dividers
- Fix: radio proactive load now works even when songs lack artistId
  (uses currentRadioArtistId module var as fallback)

UI / UX
- Click synced lyrics lines to seek (PR #38)
- Volume scroll wheel on volume slider (PR #38)
- Lyrics: active / completed / upcoming visual states (PR #38)
- Shared toast utility (src/utils/toast.ts) replaces inline toast fn
- Auto-updater: relaunch_after_update Rust command exits first to
  release single-instance lock before spawning new process

About / Credits
- nisarg-78 and JulianNymark added to contributors (since v1.29.0)
- netherguy4 added as Special Thanks for feature ideas and feedback
- i18n: aboutSpecialThanksLabel in all 5 languages

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src-tauri/src/audio.rs

@@ -229,9 +229,15 @@ impl<S: Source<Item = f32>> Source for EqualPowerFadeIn<S> {
     fn sample_rate(&self) -> u32 { self.inner.sample_rate() }
     fn total_duration(&self) -> Option<Duration> { self.inner.total_duration() }
     fn try_seek(&mut self, pos: Duration) -> Result<(), rodio::source::SeekError> {
-        // Restart the fade envelope after seeking (avoids a mid-song click if
-        // the user seeks to the very beginning while a fade was in progress).
-        self.sample_count = 0;
+        // For mid-track seeks: skip straight to unity gain so the new position
+        // plays at full volume immediately — no audible fade-in glitch.
+        // For seeks to the very start (< 100 ms): keep the micro-fade to
+        // suppress any DC-offset click from the fresh decode.
+        if pos.as_millis() < 100 {
+            self.sample_count = 0;
+        } else {
+            self.sample_count = self.fade_samples;
+        }
         self.inner.try_seek(pos)
     }
 }
@@ -478,13 +484,20 @@ impl SizedDecoder {
 
         let probed = symphonia::default::get_probe()
             .format(&hint, mss, &format_opts, &MetadataOptions::default())
-            .map_err(|e| format!("probe failed: {e}"))?;
+            .map_err(|e| {
+                let hint_str = format_hint.unwrap_or("unknown");
+                if e.to_string().to_lowercase().contains("unsupported") {
+                    format!("unsupported format: .{hint_str} files cannot be played (no demuxer)")
+                } else {
+                    format!("could not open audio stream (.{hint_str}): {e}")
+                }
+            })?;
 
         let track = probed.format
             .tracks()
             .iter()
             .find(|t| t.codec_params.codec != CODEC_TYPE_NULL)
-            .ok_or_else(|| "no supported audio track".to_string())?;
+            .ok_or_else(|| "no playable audio track found in file".to_string())?;
 
         let track_id = track.id;
         let total_duration = track.codec_params.time_base
@@ -493,7 +506,13 @@ impl SizedDecoder {
 
         let mut decoder = symphonia::default::get_codecs()
             .make(&track.codec_params, &DecoderOptions::default())
-            .map_err(|e| format!("codec init failed: {e}"))?;
+            .map_err(|e| {
+                if e.to_string().to_lowercase().contains("unsupported") {
+                    "unsupported codec: no decoder available for this audio format".to_string()
+                } else {
+                    format!("failed to initialise audio decoder: {e}")
+                }
+            })?;
 
         let mut format = probed.format;
 
@@ -505,7 +524,7 @@ impl SizedDecoder {
                 Err(symphonia::core::errors::Error::IoError(_)) => {
                     break decoder.last_decoded();
                 }
-                Err(e) => return Err(format!("first packet: {e}")),
+                Err(e) => return Err(format!("could not read audio data: {e}")),
             };
             if packet.track_id() != track_id { continue; }
             match decoder.decode(&packet) {
@@ -513,10 +532,10 @@ impl SizedDecoder {
                 Err(symphonia::core::errors::Error::DecodeError(_)) => {
                     decode_errors += 1;
                     if decode_errors > DECODE_MAX_RETRIES {
-                        return Err("too many decode errors".into());
+                        return Err("too many decode errors — file may be corrupt".into());
                     }
                 }
-                Err(e) => return Err(format!("decode: {e}")),
+                Err(e) => return Err(format!("audio decode error: {e}")),
             }
         };