fix(app_controller): use direct import for load_config_from_disk + save_config_to_disk

The de-cruft track (post_module_taxonomy_de_cruft_20260627) removed
the __getattr__ lazy-load entries for moved classes from models.py
in commit 426ba343. The migration in commit 8f11340b + 9e07fac1
handled 'from src.models import X' (85 sites) and 'models.<X>'
attribute access (44 sites) but missed 2 specific sites in
app_controller.py that use the moved config-IO functions:
 - line 5169: self.config = models.load_config_from_disk()
 - line 5181: models.save_config_to_disk(self.config)

Both functions moved to src/project.py in module_taxonomy_refactor
Phase 3b. The de-cruft track's __getattr__ removal exposed the
mismatch: the app_controller was calling models.load_config_from_disk
but the function was no longer accessible via the shim.

This commit fixes both sites:
 1. Adds 'from src.project import load_config_from_disk,
    save_config_to_disk' to the import block (next to the existing
    src.project_files import)
 2. Replaces 'models.load_config_from_disk()' with 'load_config_from_disk()'
 3. Replaces 'models.save_config_to_disk(self.config)' with
    'save_config_to_disk(self.config)'

After this commit:
 - 'from src.app_controller import AppController' works without
   AttributeError on models.load_config_from_disk
 - 'uv run sloppy.py' can complete the load_config phase of init_state

The de-cruft track's __getattr__ removal is now consistent: the
load_config_from_disk and save_config_to_disk access patterns are
eliminated from the call sites, not just hidden behind the shim.

Discovered by user: running 'uv run sloppy.py' on the de-cruft
branch produced AttributeError because app_controller.py:5169
still called models.load_config_from_disk. The user reported
'If I ran the same execution on your current branch in your
sandbox, the same thing will occur' which was correct; the bug
was on the de-cruft branch itself, not in the user's main repo.

src/app_controller.py

@@ -4,6 +4,7 @@ from src.mma import Ticket, Track, TrackState
 from src.personas import Persona
 from src.mcp_client import MCPConfiguration, RAGConfig, load_mcp_config
 from src.project_files import ContextPreset, FileItem, NamedViewPreset, Preset
+from src.project import load_config_from_disk, save_config_to_disk
 from src.tool_bias import BiasProfile
 
 import copy
@@ -5166,7 +5167,7 @@ class AppController:
   scripts/audit_no_models_config_io.py.
   [C: src/app_controller.py:AppController.__init__]
   """
-  self.config = models.load_config_from_disk()
+  self.config = load_config_from_disk()
   return self.config
 
  def save_config(self) -> None:
@@ -5178,7 +5179,7 @@ class AppController:
   scripts/audit_no_models_config_io.py.
   [C: src/app_controller.py:AppController._cb_project_save, src/app_controller.py:AppController._do_generate]
   """
-  models.save_config_to_disk(self.config)
+  save_config_to_disk(self.config)
  #endregion: --- Config I/O (single source of truth) ---
 
  #endregion: MMA (Controller)