Add domain management, reports, settings, and upload templates

- Implemented domain management page with a list of monitored domains and their DMARC, SPF, and DKIM statuses.
- Created reports page with filtering options for domain, report type, and date range, displaying DMARC reports.
- Developed settings page for IMAP configuration and DMARC policy management, including form validation and feedback.
- Added upload page for DMARC report files with drag-and-drop functionality and file type validation.
- Integrated Alpine.js for interactivity and dynamic data handling across all templates.

.gitignore

@@ -172,3 +172,17 @@ cython_debug/
 
 # PyPI configuration file
 .pypirc
+
+/node_modules
+
+/backend/node_modules
+
+# Tailwind build artifacts
+/backend/app/static/css/output.css
+/backend/app/static/css/output.css.map
+
+# NPM log files and cache
+/backend/npm-debug.log*
+/backend/yarn-debug.log*
+/backend/yarn-error.log*
+/backend/.npm/