feat(cache): centralize absolute URL generation with PMO_SERVER_URL

Replace hardcoded relative URLs and manual base_url concatenation with a unified absolute URL API via pmocache::covers_absolute_url_for() and CacheTrait::absolute_url_for().

- Add pmocache as a required dependency to pmoparadise
- Introduce absolute_url_for() and covers_absolute_url_for() helpers using PMO_SERVER_URL env var (default: http://localhost:8080)
- Update all callers to use absolute URLs for covers and audio in streaming, playlists, Qobuz, Radio France, UPnP, and server startup
- Remove redundant route_for() usage in URL construction
- Add pmocache to Cargo.lock

pmocache/src/cache_trait.rs

@@ -69,14 +69,7 @@ pub trait FileCache<C: CacheConfig>: Send + Sync {
 
     /// Retourne la route relative pour accéder à un item du cache
     ///
-    /// # Arguments
-    ///
-    /// * `pk` - Clé primaire de la piste
-    /// * `param` - Paramètre optionnel (ex: "orig", "128k", etc.)
-    ///
-    /// # Returns
-    ///
-    /// Route relative (ex: "/audio/flac/abc123" ou "/audio/tracks/abc123/orig")
+    /// Format: `/{cache_name}/{cache_type}/{pk}[/{param}]`
     fn route_for(&self, pk: &str, param: Option<&str>) -> String {
         if let Some(p) = param {
             format!("/{}/{}/{}/{}", C::cache_name(), C::cache_type(), pk, p)
@@ -85,6 +78,16 @@ pub trait FileCache<C: CacheConfig>: Send + Sync {
         }
     }
 
+    /// Retourne l'URL absolue pour accéder à un item du cache
+    ///
+    /// Utilise la variable d'environnement `PMO_SERVER_URL` comme base,
+    /// avec `http://localhost:8080` comme valeur par défaut.
+    fn absolute_url_for(&self, pk: &str, param: Option<&str>) -> String {
+        let base = std::env::var("PMO_SERVER_URL")
+            .unwrap_or_else(|_| "http://localhost:8080".to_string());
+        format!("{}{}", base.trim_end_matches('/'), self.route_for(pk, param))
+    }
+
     /// Télécharge un fichier depuis une URL et l'ajoute au cache
     ///
     /// # Arguments

pmocache/src/lib.rs

@@ -144,6 +144,22 @@ pub use cache::{
     CacheSubscription,
 };
 pub use cache_trait::{pk_from_content_header, FileCache};
+
+/// Retourne la route relative pour une cover: `/covers/image/{pk}[/{param}]`
+pub fn covers_route_for(pk: &str, param: Option<&str>) -> String {
+    if let Some(p) = param {
+        format!("/covers/image/{}/{}", pk, p)
+    } else {
+        format!("/covers/image/{}", pk)
+    }
+}
+
+/// Retourne l'URL absolue pour une cover via `PMO_SERVER_URL`
+pub fn covers_absolute_url_for(pk: &str, param: Option<&str>) -> String {
+    let base = std::env::var("PMO_SERVER_URL")
+        .unwrap_or_else(|_| "http://localhost:8080".to_string());
+    format!("{}{}", base.trim_end_matches('/'), covers_route_for(pk, param))
+}
 pub use db::{CacheEntry, DB};
 pub use download::{
     download, download_with_transformer, ingest_with_transformer, peek_header, peek_reader_header,