Baseline: full tree snapshot after git repository loss

The previous .git directory was found gutted (only info/ remained), so
history is unrecoverable locally. This commit restores version control
with the tree exactly as it stands: the working app, the preview-tracks
launcher on the artist hero, the scrollable-track-previews design bundle
(docs + approved mockups), and the Phase 0 validation artifacts.

crates/metadata/examples/cover_probe.rs

@@ -0,0 +1,44 @@
+//! Hardened cover-resolution report across a whole discography.
+//!   cargo run -p metadata --example cover_probe -- input.json output.json
+//!
+//! input.json:  { "albums": [ { "artist": "...", "title": "...", "cover": "<url>" }, ... ] }
+//! output.json: [ CoverReport, ... ]  (reference + candidates + chosen, with dHash distances)
+
+#[derive(serde::Deserialize)]
+struct Album {
+    artist: String,
+    title: String,
+    cover: Option<String>,
+}
+#[derive(serde::Deserialize)]
+struct Input {
+    albums: Vec<Album>,
+}
+
+#[tokio::main]
+async fn main() {
+    let in_path = std::env::args().nth(1).expect("input.json");
+    let out_path = std::env::args().nth(2).expect("output.json");
+    let raw = std::fs::read_to_string(&in_path).expect("read input");
+    let input: Input =
+        serde_json::from_str(raw.trim_start_matches('\u{feff}')).expect("parse input");
+
+    let client = metadata::MetadataClient::new();
+    let mut reports = Vec::new();
+    let total = input.albums.len();
+    for (i, a) in input.albums.iter().enumerate() {
+        let reference = a.cover.clone().unwrap_or_default();
+        let report = client.cover_report(&a.artist, &a.title, &reference).await;
+        eprintln!(
+            "[{}/{}] {} :: chosen={:?} ({} candidates)",
+            i + 1,
+            total,
+            a.title,
+            report.chosen_source,
+            report.candidates.len()
+        );
+        reports.push(report);
+    }
+    std::fs::write(&out_path, serde_json::to_string(&reports).unwrap()).expect("write output");
+    eprintln!("wrote {out_path}");
+}