Replaces the duplicated primary/billing/technical checks across portal pages, post.php handlers, nav, and dashboard with contactCan()/enforceContactCan(). Same behavior, but the rules now live in one place instead of being copy-pasted, which is what let them drift before. file.php keeps its 404 response; ticket-visibility and approval-routing checks are intentionally left as-is.
- Implemented file upload capabilities, allowing users to attach files to documents with support for various formats (PDF, Word, text).
- Created modals for adding new documents and uploading files, improving user experience.
- Added functions for formatting file sizes and retrieving appropriate icons based on file extensions.
- Updated the document display logic to handle attached files, providing inline previews for PDFs and images.
