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/log_service.py

@@ -21,7 +21,6 @@ from sqlalchemy.orm import Session
 from app.core.config import settings
 from app.exceptions import ResourceNotFoundException
 from app.modules.tenancy.exceptions import AdminOperationException
-from app.modules.tenancy.models import ApplicationLog
 from app.modules.tenancy.schemas.admin import (
     ApplicationLogFilters,
     ApplicationLogListResponse,
@@ -33,6 +32,13 @@ from app.modules.tenancy.schemas.admin import (
 logger = logging.getLogger(__name__)
 
 
+def _get_application_log_model():
+    """Deferred import for ApplicationLog model (lives in tenancy, consumed by monitoring)."""
+    from app.modules.tenancy.models import ApplicationLog
+
+    return ApplicationLog
+
+
 class LogService:
     """Service for managing application logs."""
 
@@ -49,6 +55,7 @@ class LogService:
         Returns:
             Paginated list of logs
         """
+        ApplicationLog = _get_application_log_model()
         try:
             query = db.query(ApplicationLog)
 
@@ -125,6 +132,7 @@ class LogService:
         Returns:
             Log statistics
         """
+        ApplicationLog = _get_application_log_model()
         try:
             cutoff_date = datetime.now(UTC) - timedelta(days=days)
 
@@ -329,6 +337,7 @@ class LogService:
         Returns:
             Number of logs deleted
         """
+        ApplicationLog = _get_application_log_model()
         try:
             cutoff_date = datetime.now(UTC) - timedelta(days=retention_days)
 
@@ -356,6 +365,7 @@ class LogService:
 
     def delete_log(self, db: Session, log_id: int) -> str:
         """Delete a specific log entry."""
+        ApplicationLog = _get_application_log_model()
         try:
             log_entry = (
                 db.query(ApplicationLog).filter(ApplicationLog.id == log_id).first()