feat(meta): look up series external ids

crates/arr-meta/src/model.rs

@@ -218,9 +218,16 @@ pub(crate) struct RawSeries {
     external_ids: Option<RawExternalIds>,
 }
 
+/// The slice of `/tv/{id}/external_ids` this project reads.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct ExternalIds {
+    /// The Torznab `tvdbid` parameter (§6.1), when TMDB knows one.
+    pub tvdb_id: Option<u32>,
+}
+
 #[derive(Debug, Deserialize)]
-struct RawExternalIds {
-    tvdb_id: Option<u32>,
+pub(crate) struct RawExternalIds {
+    pub(crate) tvdb_id: Option<u32>,
 }
 
 #[derive(Debug, Deserialize)]