fix: Enable compact UI output for plan_approve tool

Added plan_approve to the compact tool list in format_tool_result_summary()
so it displays in the same format as other tools like read_file and write_file.

The format_plan_approve_summary() function already existed but was never
called because plan_approve was missing from the matches! block.

crates/g3-core/src/streaming.rs

@@ -74,6 +74,7 @@ pub fn format_tool_result_summary(
             | "coverage"
             | "rehydrate"
             | "code_search"
+            | "plan_approve"
     );
 
     if is_todo_tool {