refactor(qconnect): hoist queue-track / volume / loop-mode mappers into qconnect-app (slice 6)

Move the pure protocol mappers model_track_to_core_queue_track,
normalize_volume_to_fraction, qconnect_repeat_mode_from_loop_mode (+ the
QCONNECT_REMOTE_QUEUE_SOURCE tag) into qconnect-app/src/renderer.rs so the
renderer orchestration that calls them (hoisted in a later step) can live there
too. The src-tauri mod.rs re-exports them, so corebridge + tests compile
unchanged. The load-dedup predicates and audio-quality report helpers move
alongside their orchestration / report consumers in the next steps (cohesion +
avoids churning the AUDIO_QUALITY_* consts now).

src-tauri qconnect 42 green.

cc

crates/qconnect-app/src/lib.rs

@@ -7,6 +7,7 @@ mod error;
 mod events;
 mod feature_flags;
 pub mod queue_resolution;
+pub mod renderer;
 mod renderer_engine;
 pub mod session;
 mod state;

crates/qconnect-app/src/renderer.rs

@@ -0,0 +1,74 @@
+//! Frontend-agnostic renderer-side pure helpers (slice 6).
+//!
+//! Pure protocol/format math used by the renderer orchestration (queue
+//! materialize / cursor-align). No engine, no I/O, no Tauri. Relocated here so
+//! both the Tauri adapter and the Slint adapter share one definition; the
+//! src-tauri side re-exports these. The load-dedup predicates and the
+//! audio-quality report helpers move here alongside their orchestration /
+//! report consumers in the later slice-6 steps.
+
+use qbz_models::{QueueTrack, RepeatMode, Track};
+
+/// Source tag stamped on remote queue tracks materialized from a QConnect cloud
+/// queue. Matches the Tauri adapter's prior `QCONNECT_REMOTE_QUEUE_SOURCE`.
+pub const QCONNECT_REMOTE_QUEUE_SOURCE: &str = "qobuz_connect_remote";
+
+pub fn qconnect_repeat_mode_from_loop_mode(loop_mode: i32) -> Option<RepeatMode> {
+    // QConnect protocol loop mode values: 1 = off, 2 = repeat one, 3 = repeat all.
+    match loop_mode {
+        0 | 1 => Some(RepeatMode::Off),
+        2 => Some(RepeatMode::One),
+        3 => Some(RepeatMode::All),
+        _ => None,
+    }
+}
+
+pub fn normalize_volume_to_fraction(volume: i32) -> f32 {
+    volume.clamp(0, 100) as f32 / 100.0
+}
+
+pub fn model_track_to_core_queue_track(track: &Track) -> QueueTrack {
+    let artwork_url = track
+        .album
+        .as_ref()
+        .and_then(|album| album.image.best().cloned());
+    let artist = track
+        .performer
+        .as_ref()
+        .map(|performer| performer.name.clone())
+        .unwrap_or_else(|| "Unknown Artist".to_string());
+    let album = track
+        .album
+        .as_ref()
+        .map(|album| album.title.clone())
+        .unwrap_or_else(|| "Unknown Album".to_string());
+    let album_id = track.album.as_ref().and_then(|album| {
+        let trimmed = album.id.trim();
+        if trimmed.is_empty() {
+            None
+        } else {
+            Some(trimmed.to_string())
+        }
+    });
+    let artist_id = track.performer.as_ref().map(|performer| performer.id);
+
+    QueueTrack {
+        id: track.id,
+        title: track.title.clone(),
+        version: track.version.clone(),
+        artist,
+        album,
+        duration_secs: track.duration as u64,
+        artwork_url,
+        hires: track.hires,
+        bit_depth: track.maximum_bit_depth,
+        sample_rate: track.maximum_sampling_rate,
+        is_local: false,
+        album_id: album_id.clone(),
+        artist_id,
+        streamable: track.streamable,
+        source: Some(QCONNECT_REMOTE_QUEUE_SOURCE.to_string()),
+        parental_warning: track.parental_warning,
+        source_item_id_hint: album_id,
+    }
+}