feat: add head/tail/line range options to content endpoints

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/services/async_item_service.rs

@@ -282,13 +282,32 @@ impl AsyncItemService {
     pub async fn get_item_content_info_streaming(
         &self,
         item_id: i64,
+        head_bytes: Option<usize>,
+        head_words: Option<usize>,
+        head_lines: Option<usize>,
+        tail_bytes: Option<usize>,
+        tail_words: Option<usize>,
+        tail_lines: Option<usize>,
+        line_start: Option<usize>,
+        line_end: Option<usize>,
     ) -> Result<(Box<dyn Read + Send>, String, bool), CoreError> {
         let db = self.db.clone();
         let item_service = self.item_service.clone();
 
         tokio::task::spawn_blocking(move || {
             let conn = db.blocking_lock();
-            item_service.get_item_content_info_streaming(&conn, item_id)
+            item_service.get_item_content_info_streaming(
+                &conn, 
+                item_id, 
+                head_bytes, 
+                head_words, 
+                head_lines, 
+                tail_bytes, 
+                tail_words, 
+                tail_lines, 
+                line_start, 
+                line_end
+            )
         })
         .await
         .unwrap()