feat(poster-fetcher): add poster fetcher adapter with configuration and integration

crates/adapters/poster-fetcher/src/config.rs

@@ -0,0 +1,13 @@
+pub struct PosterFetcherConfig {
+    pub timeout_seconds: u64,
+}
+
+impl PosterFetcherConfig {
+    pub fn from_env() -> Self {
+        let timeout_seconds = std::env::var("POSTER_FETCH_TIMEOUT_SECONDS")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(30);
+        Self { timeout_seconds }
+    }
+}