feat: add rest api for music tracks

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/claude-agent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/services/mod.rs

@@ -0,0 +1,45 @@
+use uuid::Uuid;
+
+use crate::models::Track;
+
+#[derive(Default)]
+pub struct Aggregator {
+    tracks: Vec<Track>,
+}
+
+impl Aggregator {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn add_track(&mut self, track: Track) -> Track {
+        self.tracks.push(track.clone());
+        track
+    }
+
+    pub fn get_all(&self) -> &[Track] {
+        &self.tracks
+    }
+
+    pub fn get_by_id(&self, id: Uuid) -> Option<&Track> {
+        self.tracks.iter().find(|t| t.id == id)
+    }
+
+    pub fn search_by_artist(&self, artist: &str) -> Vec<&Track> {
+        let artist_lower = artist.to_lowercase();
+        self.tracks
+            .iter()
+            .filter(|t| t.artist.to_lowercase().contains(&artist_lower))
+            .collect()
+    }
+
+    pub fn delete(&mut self, id: Uuid) -> bool {
+        let len_before = self.tracks.len();
+        self.tracks.retain(|t| t.id != id);
+        self.tracks.len() != len_before
+    }
+
+    pub fn total_duration(&self) -> u32 {
+        self.tracks.iter().map(|t| t.duration_secs).sum()
+    }
+}