feat(bridge): add init_cache, download_avatar, and cache management functions

- Add init_cache(dir) bridge function
- Add download_avatar(avatar_hash, client_uid) bridge function
- Add clear_file_cache() and file_cache_size() bridge functions
- Map CoreError::Cache and ProtocolError::FileTransfer in BridgeError

crates/chanora_bridge/src/api.rs

@@ -1465,6 +1465,45 @@ pub async fn init_storage(dir: String) -> Result<(), BridgeError> {
     Ok(())
 }
 
+/// Configure the bridge blob cache root.
+pub async fn init_cache(dir: String) -> Result<(), BridgeError> {
+    runtime()
+        .spawn(async move { session().init_cache(&dir).await })
+        .await
+        .map_err(|e| task_join_error("init_cache", e))??;
+    Ok(())
+}
+
+/// Resolve avatar bytes through the bridge.
+pub async fn download_avatar(
+    avatar_hash: String,
+    client_uid: String,
+) -> Result<Option<Vec<u8>>, BridgeError> {
+    runtime()
+        .spawn(async move { session().get_avatar(&avatar_hash, &client_uid).await })
+        .await
+        .map_err(|e| task_join_error("download_avatar", e))?
+        .map_err(BridgeError::from)
+}
+
+/// Purge cached protocol-owned assets.
+pub async fn clear_file_cache() -> Result<(), BridgeError> {
+    runtime()
+        .spawn(async move { session().clear_cache().await })
+        .await
+        .map_err(|e| task_join_error("clear_file_cache", e))??;
+    Ok(())
+}
+
+/// Report the configured file-cache size.
+pub async fn file_cache_size() -> Result<u64, BridgeError> {
+    runtime()
+        .spawn(async move { session().cache_size().await })
+        .await
+        .map_err(|e| task_join_error("file_cache_size", e))?
+        .map_err(BridgeError::from)
+}
+
 /// Bookmark DTO mirroring [`chanora_core::Bookmark`].
 #[derive(Debug, Clone)]
 pub struct BridgeBookmark {

crates/chanora_bridge/src/lib.rs

@@ -110,9 +110,13 @@ impl From<chanora_core::CoreError> for BridgeError {
                 code,
                 message,
             }) => BridgeError::ServerRejected { code, message },
+            chanora_core::CoreError::Protocol(chanora_core::ProtocolError::FileTransfer(p)) => {
+                BridgeError::Connection(format!("file transfer: {p}"))
+            }
             chanora_core::CoreError::Protocol(p) => BridgeError::Connection(format!("{p}")),
             chanora_core::CoreError::Audio(a) => BridgeError::Connection(format!("audio: {a}")),
             chanora_core::CoreError::Storage(s) => BridgeError::Connection(format!("storage: {s}")),
+            chanora_core::CoreError::Cache(c) => BridgeError::Connection(format!("cache: {c}")),
             other => BridgeError::Unmapped(format!("{other}")),
         }
     }