offline updates and playhead fix

lib/widgets/art_image.dart

@@ -0,0 +1,95 @@
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+
+import '../theme/tokens.dart';
+
+/// Cover art that renders from EITHER a local file (`file://` URI) or a network
+/// URL, picking [FileImage] vs [NetworkImage] purely by the URI scheme. This is
+/// the single place all art-rendering call sites go through, so a downloaded
+/// track's art shows offline (the caller hands us the already-built URI string;
+/// resolving download-vs-network happens upstream in `providers.dart`).
+///
+/// Behaviour preserved from the old scattered `Image.network(...)` call sites:
+///   * `fit: BoxFit.cover`, `gaplessPlayback: true`, and a `ValueKey(uri)` so
+///     switching tracks keeps the previous frame until the new art decodes (no
+///     flash) and rebuilds cleanly.
+///   * a surface-filled [placeholder] with a muted album icon for the null,
+///     loading-error, and missing-file cases (via `errorBuilder`).
+///
+/// Sizing is never hardcoded — [width]/[height]/[fit] are respected as passed.
+/// Optional [borderRadius] clips the art with a [ClipRRect]; callers that pass
+/// it should drop their own outer `ClipRRect` so we don't double-clip.
+class ArtImage extends StatelessWidget {
+  const ArtImage(
+    this.uri, {
+    super.key,
+    this.fit = BoxFit.cover,
+    this.width,
+    this.height,
+    this.placeholder,
+    this.borderRadius,
+  });
+
+  /// The already-built art URI. A `file://` URI loads from disk; anything else
+  /// (http/https) loads over the network. `null` → [placeholder].
+  final String? uri;
+
+  final BoxFit fit;
+  final double? width;
+  final double? height;
+
+  /// Shown for null/error/missing art. Defaults to [_ArtPlaceholder].
+  final Widget? placeholder;
+
+  /// If set, the art (and placeholder) are clipped to these rounded corners.
+  final BorderRadius? borderRadius;
+
+  @override
+  Widget build(BuildContext context) {
+    final fallback = placeholder ?? const _ArtPlaceholder();
+
+    Widget child;
+    if (uri == null) {
+      child = fallback;
+    } else {
+      final parsed = Uri.tryParse(uri!);
+      final ImageProvider provider = (parsed != null && parsed.scheme == 'file')
+          ? FileImage(File(parsed.toFilePath()))
+          : NetworkImage(uri!);
+      child = Image(
+        image: provider,
+        key: ValueKey(uri),
+        fit: fit,
+        gaplessPlayback: true,
+        errorBuilder: (_, _, _) => fallback,
+      );
+    }
+
+    // Back the art with the surface fill so transparent/loading gaps read as
+    // a panel rather than the bare canvas (matches the old ColoredBox wrap).
+    child = ColoredBox(color: TimbreColors.surface, child: child);
+
+    if (width != null || height != null) {
+      child = SizedBox(width: width, height: height, child: child);
+    }
+    if (borderRadius != null) {
+      child = ClipRRect(borderRadius: borderRadius!, child: child);
+    }
+    return child;
+  }
+}
+
+/// The default art placeholder: a muted album glyph on the surface fill. Used
+/// for null art and as the loading/error fallback.
+class _ArtPlaceholder extends StatelessWidget {
+  const _ArtPlaceholder();
+
+  @override
+  Widget build(BuildContext context) => ColoredBox(
+    color: TimbreColors.surface,
+    child: Center(
+      child: Icon(Icons.album_outlined, color: TimbreColors.dimmed),
+    ),
+  );
+}