fix(server): stop stacking a tool profile's visibility on every session

What the first Linux CI run of the 1.6 tree found.

- fastmcp 3's enable()/disable() append a Visibility transform per call,
  and a tool lookup walks the transform stack as nested calls. The
  lifespan re-applies the tool profile on every client connection, so an
  in-process server grew two layers per session until every tool call,
  system_status included, raised RecursionError (CPython 3.11 counts C
  frames against the limit). The profile's transforms now replace the
  previous ones, as _apply_discovery_mode already did; a test switches
  the profile 600 times and then calls a tool. The local suite runs in
  half the time it took with the stack growing.
- 21 fake-ActiveX tests build a real pywin32 VARIANT; they now skip
  without pywin32, like the suite's other VARIANT-dependent COM tests,
  and the Windows lane keeps running them.
- A test spelled a path through a directory it never created, which only
  Windows normalises away; it creates the directory.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd

tests/test_documents.py

@@ -190,6 +190,9 @@ async def test_save_to_the_document_own_path_is_not_a_collision(backend, tmp_pat
     assert (await backend.drawing_save(str(path)))["ok"] is True
     await backend.entity_create_circle(0, 0, 3)
     # A spelling that differs from the key still names the same file.
+    # POSIX resolves sub/.. through the directory, so it must exist; Windows
+    # normalises the spelling before it looks.
+    (tmp_path / "sub").mkdir()
     spelled = str(tmp_path / "sub" / ".." / "self.dxf")
     assert (await backend.drawing_save_as(spelled))["ok"] is True
     assert len(await backend.document_list()) == 2