refactor(arch): eliminate all cross-module model imports in service layer

Enforce MOD-025/MOD-026 rules: zero top-level cross-module model imports
remain in any service file. All 66 files migrated using deferred import
patterns (method-body, _get_model() helpers, instance-cached self._Model)
and new cross-module service methods in tenancy. Documentation updated
with Pattern 6 (deferred imports), migration plan marked complete, and
violations status reflects 84→0 service-layer violations.

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

app/modules/monitoring/services/admin_audit_service.py

@@ -8,6 +8,8 @@ This module provides functions for:
 - Generating audit reports
 """
 
+from __future__ import annotations
+
 import logging
 from typing import Any
 
@@ -16,7 +18,6 @@ from sqlalchemy.exc import SQLAlchemyError
 from sqlalchemy.orm import Session
 
 from app.modules.tenancy.exceptions import AdminOperationException
-from app.modules.tenancy.models import AdminAuditLog, User
 from app.modules.tenancy.schemas.admin import (
     AdminAuditLogFilters,
     AdminAuditLogResponse,
@@ -25,6 +26,13 @@ from app.modules.tenancy.schemas.admin import (
 logger = logging.getLogger(__name__)
 
 
+def _get_audit_log_model():
+    """Deferred import for AdminAuditLog model (lives in tenancy, consumed by monitoring)."""
+    from app.modules.tenancy.models import AdminAuditLog
+
+    return AdminAuditLog
+
+
 class AdminAuditService:
     """Service for admin audit logging."""
 
@@ -57,6 +65,7 @@ class AdminAuditService:
         Returns:
             Created AdminAuditLog instance
         """
+        AdminAuditLog = _get_audit_log_model()
         try:
             audit_log = AdminAuditLog(
                 admin_user_id=admin_user_id,
@@ -98,9 +107,12 @@ class AdminAuditService:
         Returns:
             List of audit log responses
         """
+        AdminAuditLog = _get_audit_log_model()
         try:
-            query = db.query(AdminAuditLog).join(
-                User, AdminAuditLog.admin_user_id == User.id
+            from sqlalchemy.orm import joinedload
+
+            query = db.query(AdminAuditLog).options(
+                joinedload(AdminAuditLog.admin_user)
             )
 
             # Apply filters
@@ -158,6 +170,7 @@ class AdminAuditService:
 
     def get_audit_logs_count(self, db: Session, filters: AdminAuditLogFilters) -> int:
         """Get total count of audit logs matching filters."""
+        AdminAuditLog = _get_audit_log_model()
         try:
             query = db.query(AdminAuditLog)
 
@@ -199,6 +212,7 @@ class AdminAuditService:
         self, db: Session, target_type: str, target_id: str, limit: int = 50
     ) -> list[AdminAuditLogResponse]:
         """Get all actions performed on a specific target."""
+        AdminAuditLog = _get_audit_log_model()
         try:
             logs = (
                 db.query(AdminAuditLog)