feat(mma): Phase 2 — migrate _render_tool_calls_panel to dict access

Replace tuple destructure 'script, result, _ = self._tool_log[i]'
with dict access 'entry = self._tool_log[i]; script = entry[script]; result = entry[result]'
Prerequisite for Phase 3 filter logic.

gui_2.py

@@ -2971,7 +2971,9 @@ class App:
   clipper.begin(len(self._tool_log))
   while clipper.step():
    for i_minus_one in range(clipper.display_start, clipper.display_end):
-    i = i_minus_one + 1
+    entry = self._tool_log[i_minus_one]
+    script = entry["script"]
+    result = entry["result"]
     script, result, _ = self._tool_log[i_minus_one]
     first_line = script.strip().splitlines()[0][:80] if script.strip() else "(empty)"
     imgui.text_colored(C_KEY, f"Call #{i}: {first_line}")