fix: resolve compiler warnings across crates

- Remove unused assignment to final_output_called (returns immediately after)
- Mark cache_config field as #[allow(dead_code)] (reserved for future use)
- Mark print_status_line method as #[allow(dead_code)] (reserved for future use)

crates/g3-planner/src/llm.rs

@@ -206,6 +206,7 @@ impl PlannerUiWriter {
     }
     
     /// Clear the current line and print a status message
+    #[allow(dead_code)]
     fn print_status_line(&self, message: &str) {
         // Print status message without overwriting previous content
         // Use println to ensure each status is on its own line