fix: make the patched get_default_project_directory order-safe in tests

A product module first-imported while run_around_tests' autouse
monkeypatch of gns3server.utils.path.get_default_project_directory is
active (e.g. 'from gns3server.api.server import app' inside a test body)
binds the patched lambda into its own namespace forever: module-level
from-imports capture the object by value. Once the patch is reverted,
that module keeps calling the stale lambda, which closed over the very
test's tmppath — a directory deleted at that test's teardown. Every
later test hitting psutil.disk_usage(get_default_project_directory())
then fails with FileNotFoundError, but only when the importing test runs
before the API test files (full-suite collection order hides it).

The replacement now resolves Config.instance().settings at call time
instead of closing over the tmppath, so a frozen reference stays
correct; the test that triggered this imports gns3_app at module top
so no product import ever happens inside a patched window.

Also pins pytest-random-order (inert without --random-order) and
documents the order-independence rules for new tests in the
gns3-api-test-writing skill, including the known-red legacy files
whose tests share rows sequentially.

tests/controller/test_compute.py

@@ -25,6 +25,7 @@ from unittest.mock import patch, MagicMock
 
 from gns3server.controller.project import Project
 from gns3server.controller.compute import Compute
+from gns3server.api.server import app as gns3_app
 from gns3server.controller.controller_error import (
     ControllerError,
     ControllerNotFoundError,
@@ -581,8 +582,10 @@ async def test_connect_notification_poison_frame_autoreconnects(compute, monkeyp
     compute._http_session = session
 
     # allow the reconnection to be scheduled during the test
+    # (import gns3_app at module top: a first import from inside a test body
+    #  would execute module-level from-imports while the autouse fixture's
+    #  monkeypatches are active, freezing patched objects into namespaces)
     monkeypatch.delattr(sys, "_called_from_test", raising=False)
-    from gns3server.api.server import app as gns3_app
     monkeypatch.setattr(gns3_app.state, "exiting", False)
 
     async def fake_connect():