feat: config crate with legacy env names

crates/config/src/metadata_config.rs

@@ -0,0 +1,43 @@
+use std::fmt;
+
+use serde::Deserialize;
+
+use crate::lenient;
+
+#[derive(Clone, Deserialize)]
+#[serde(default)]
+pub struct MetadataConfig {
+    pub tmdb_api_key: Option<String>,
+    pub omdb_api_key: Option<String>,
+    #[serde(deserialize_with = "lenient::number")]
+    pub poster_fetch_timeout_seconds: u64,
+}
+
+impl Default for MetadataConfig {
+    fn default() -> Self {
+        Self {
+            tmdb_api_key: None,
+            omdb_api_key: None,
+            poster_fetch_timeout_seconds: 30,
+        }
+    }
+}
+
+impl fmt::Debug for MetadataConfig {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("MetadataConfig")
+            .field(
+                "tmdb_api_key",
+                &self.tmdb_api_key.as_ref().map(|_| "<redacted>"),
+            )
+            .field(
+                "omdb_api_key",
+                &self.omdb_api_key.as_ref().map(|_| "<redacted>"),
+            )
+            .field(
+                "poster_fetch_timeout_seconds",
+                &self.poster_fetch_timeout_seconds,
+            )
+            .finish()
+    }
+}