fix(test): patch MEMORY_INDEX alongside MEMORY_DIR in import tests

The two new memory_import tests monkeypatched mem.MEMORY_DIR but not
mem.MEMORY_INDEX (a Path constant frozen at import time). _write_index()
inside handle_memory_import then wrote to the original
~/.tdpilot-api/memory/MEMORY.md location. On my dev machine the dir
exists, so the tests silently wrote there and passed. On CI's fresh
runner the dir doesn't exist → FileNotFoundError.

Fix: monkeypatch both MEMORY_DIR and MEMORY_INDEX. Same pattern as the
existing tests would benefit from but they don't trigger _write_index.

Author: dreamrec

tests/test_tdpilot_api_memory.py

@@ -120,6 +120,7 @@ def test_memory_export_dumps_all_files(tmp_path, monkeypatch):
 
 def test_memory_import_skips_existing_by_default(tmp_path, monkeypatch):
     monkeypatch.setattr(mem, "MEMORY_DIR", tmp_path)
+    monkeypatch.setattr(mem, "MEMORY_INDEX", tmp_path / "MEMORY.md")
     _seed(tmp_path, "user_role.md", "old", "old body", mtype="user")
 
     payload = {
@@ -145,6 +146,7 @@ def test_memory_import_skips_existing_by_default(tmp_path, monkeypatch):
 
 def test_memory_import_overwrite_replaces_existing(tmp_path, monkeypatch):
     monkeypatch.setattr(mem, "MEMORY_DIR", tmp_path)
+    monkeypatch.setattr(mem, "MEMORY_INDEX", tmp_path / "MEMORY.md")
     _seed(tmp_path, "user_role.md", "old", "old body", mtype="user")
 
     payload = {