refactor: remove legacy models/schema/auth.py re-export file

All 84 import sites now use the canonical path
app.modules.tenancy.schemas.auth directly — no need
for backwards-compatibility re-exports.

Update audit validator to check module schemas locations
instead of only the legacy models/schema/ path.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

models/schema/__init__.py

@@ -23,7 +23,6 @@ Import schemas from their canonical module locations instead of this package.
 
 # Infrastructure schemas that remain here
 from . import (
-    auth,
     base,
 )
 
@@ -32,5 +31,4 @@ from .base import *  # Base Pydantic models
 
 __all__ = [
     "base",
-    "auth",
 ]