refactor(consumers): replace 'models.<moved_class>' with direct imports

Per post_module_taxonomy_de_cruft_20260627 Phase 2 (FR7 continued).
The previous migration commit (8f11340b) handled the
'from src.models import X' pattern (85 sites). This commit handles
the 'models.<moved_class>' attribute access pattern (44 sites in 20
files), which the __getattr__ shim previously supported.

The migration was performed by the one-time script
scripts/tier2/artifacts/post_module_taxonomy_de_cruft_20260627/migrate_models_attr.py
which:
 1. For each 'models.<moved_class>' reference, replaces it with the
    bare class name (e.g., 'models.MCPConfiguration' -> 'MCPConfiguration')
 2. Adds the import 'from src.<destination> import <moved_class>' at
    the top of the file (deduplicated if the import already exists)
 3. Skips moved classes that the file already imports directly

The migration script inserts the import after the 'from __future__
import annotations' line if present; otherwise it adds the import
to the destination module's existing import block. Two files
required manual fixes because the script's regex didn't handle them:
 - src/rag_engine.py: uses 'from src import models' (not 'from
                            src.models import X'); the class is accessed
                            via 'models.RAGConfig'. Replaced with a
                            direct 'from src.mcp_client import RAGConfig'
                            import and removed the 'from src import models'.
 - tests/test_project_context_20260627.py: uses the parens-style
                            multi-line 'from src.models import (X, Y, Z)'.
                            Replaced with the parens-style direct import.

After this commit:
 - 'models.MCPConfiguration', 'models.FileItem', 'models.Ticket', etc.
   no longer work in src/ and tests/ (the AttributeError raises
   because models.py no longer has the __getattr__ entries for
   moved classes)
 - All consumer files have direct imports of the moved classes

Total: 44 'models.<moved_class>' references rewritten across 20 files.

tests/test_project_serialization.py

@@ -17,8 +17,8 @@ class TestProjectSerialization(unittest.TestCase):
  def test_fileitem_roundtrip(self):
   """Verify that FileItem objects survive a save/load cycle."""
   proj = project_manager.default_project("test")
-  file1 = models.FileItem(path="src/main.py", auto_aggregate=True, force_full=False)
-  file2 = models.FileItem(path="docs/readme.md", auto_aggregate=False, force_full=True)
+  file1 = FileItem(path="src/main.py", auto_aggregate=True, force_full=False)
+  file2 = FileItem(path="docs/readme.md", auto_aggregate=False, force_full=True)
   proj["files"]["paths"] = [file1, file2]
   
   # Save
@@ -29,12 +29,12 @@ class TestProjectSerialization(unittest.TestCase):
   
   paths = loaded_proj["files"]["paths"]
   self.assertEqual(len(paths), 2)
-  self.assertIsInstance(paths[0], models.FileItem)
+  self.assertIsInstance(paths[0], FileItem)
   self.assertEqual(paths[0].path, "src/main.py")
   self.assertTrue(paths[0].auto_aggregate)
   self.assertFalse(paths[0].force_full)
   
-  self.assertIsInstance(paths[1], models.FileItem)
+  self.assertIsInstance(paths[1], FileItem)
   self.assertEqual(paths[1].path, "docs/readme.md")
   self.assertFalse(paths[1].auto_aggregate)
   self.assertTrue(paths[1].force_full)
@@ -68,17 +68,17 @@ roles = ["User", "AI"]
   raw_paths = controller.project.get("files", {}).get("paths", [])
   controller.files = []
   for p in raw_paths:
-   if isinstance(p, models.FileItem):
+   if isinstance(p, FileItem):
     controller.files.append(p)
    elif isinstance(p, dict):
-    controller.files.append(models.FileItem.from_dict(p))
+    controller.files.append(FileItem.from_dict(p))
    else:
-    controller.files.append(models.FileItem(path=str(p)))
+    controller.files.append(FileItem(path=str(p)))
     
   self.assertEqual(len(controller.files), 2)
-  self.assertIsInstance(controller.files[0], models.FileItem)
+  self.assertIsInstance(controller.files[0], FileItem)
   self.assertEqual(controller.files[0].path, "file1.py")
-  self.assertIsInstance(controller.files[1], models.FileItem)
+  self.assertIsInstance(controller.files[1], FileItem)
   self.assertEqual(controller.files[1].path, "file2.md")
 
  def test_default_roles_include_context(self):