Separate tool name from output across all agent sessions (s03-s_full)

Extends the readability fix from PR #128 (s02) to all remaining sessions.
Tool name and output are now on separate lines, consistent with s01's
existing pattern and improving readability for multi-line tool output.

agents/s12_worktree_task_isolation.py

@@ -747,7 +747,8 @@ def agent_loop(messages: list):
                     output = handler(**block.input) if handler else f"Unknown tool: {block.name}"
                 except Exception as e:
                     output = f"Error: {e}"
-                print(f"> {block.name}: {str(output)[:200]}")
+                print(f"> {block.name}:")
+                print(str(output)[:200])
                 results.append(
                     {
                         "type": "tool_result",