feat: Add report templates API for CRUD operations and implement SLM settings modal

- Implemented a new API router for managing report templates, including endpoints for listing, creating, retrieving, updating, and deleting templates.
- Added a new HTML partial for a unified SLM settings modal, allowing users to configure SLM settings with dynamic modem selection and FTP credentials.
- Created a report preview page with an editable data table using jspreadsheet, enabling users to modify report details and download the report as an Excel file.

backend/main.py

@@ -101,6 +101,10 @@ app.include_router(projects.router)
 app.include_router(project_locations.router)
 app.include_router(scheduler.router)
 
+# Report templates router
+from backend.routers import report_templates
+app.include_router(report_templates.router)
+
 # Start scheduler service on application startup
 from backend.services.scheduler import start_scheduler, stop_scheduler