fix: Implement missing options trait for filter plugins

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

src/filter_plugin/head.rs

@@ -95,4 +95,14 @@ impl FilterPlugin for HeadLinesFilter {
             remaining: self.remaining,
         })
     }
+    
+    fn options(&self) -> Vec<FilterOption> {
+        vec![
+            FilterOption {
+                name: "count".to_string(),
+                default: None,
+                required: true,
+            }
+        ]
+    }
 }

src/filter_plugin/skip.rs

@@ -134,4 +134,14 @@ impl FilterPlugin for SkipLinesFilter {
             remaining: self.remaining,
         })
     }
+    
+    fn options(&self) -> Vec<FilterOption> {
+        vec![
+            FilterOption {
+                name: "count".to_string(),
+                default: None,
+                required: true,
+            }
+        ]
+    }
 }