refactor(tests): per-model fakes, FakeMCP and session mocks come from tests/helpers (#2825, milestone 296 area 1, batch 2)

Second pass over the tests/ ledger after bbee0d0. fake_record(**attrs) is the
one MagicMock-with-real-attributes builder (to_dict mirrors them; the
note-2109 hazard documented once); fake_note/fake_task/fake_snippet/
fake_project/fake_milestone/fake_system/fake_rulebook/fake_topic/fake_rule
carry each model's ordinary defaults on top of it, replacing 14 per-file
factories (two rulebook trios in tool-vs-service wordings, _fake_task, _fake_ms,
_fake_project, _plan_note, _fake_snippet, two _snippet adapters now one-liners
over fake_snippet). FakeMCP replaces the five closure-over-a-list registrar
fakes (+ _Recorder); loc() and design_token_stub() replace the paired _loc /
_token / _T stand-ins; every hand-built async_session mock (9 helper defs and
14 inline copies) now starts from make_mock_session(). Call sites rewritten by
AST with each file's former defaults made explicit, so behaviour is unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_routes_design_systems.py

@@ -5,6 +5,7 @@ deliberate: relaxing one to a pattern would stop it catching the thing it was
 written for, which is a capability landing on one surface and not the other.
 """
 import inspect
+from tests.helpers import FakeMCP
 
 
 def test_design_systems_blueprint_registered():
@@ -107,17 +108,12 @@ def test_every_mcp_tool_in_the_module_is_registered():
     else in the codebase would notice."""
     from scribe.mcp.tools import design_systems as tools
 
-    registered = []
+    mcp = FakeMCP()
 
-    class _Recorder:
-        def tool(self, name):
-            registered.append(name)
-            return lambda fn: fn
-
-    tools.register(_Recorder())
+    tools.register(mcp)
 
     public = {
         name for name, obj in vars(tools).items()
         if inspect.iscoroutinefunction(obj) and not name.startswith("_")
     }
-    assert set(registered) == public
+    assert set(mcp.names) == public