DSM Frontend QA Batch: Rich-Text Email Composer, Sync-to-Payments, PDF Viewer & Grid Improvements

This release promotes a large batch of DSM web app improvements from Dev to QA. Highlights include a full rich-text editor for composing shared emails, the ability to sync mail documents to the Payments (PTP) system individually or in bulk, a substantially upgraded in-app PDF viewer, a redesigned login experience, and numerous data-grid and loading-state refinements.

Several gaps in the existing experience were addressed at once: emails shared from DSM could only be plain text, document-to-payments syncing was not available from the mail Documents tab, the PDF viewer lacked common controls (zoom/fit/rotate), long values in grids were hard to read, and loading states were inconsistent. The batch also standardizes API request URLs to reduce avoidable backend redirects.

Users gain a formatted email composer (bold, lists, headings, colors, images) when sharing mail; can sync documents to Promise-to-Pay from the Documents tab with single and bulk actions plus a visible "synced by" indicator; get a more capable PDF viewer (inline zoom, fit-to-width, orientation toggle, tooltips, screen-reader labels); see truncated long fields with hover tooltips and searchable, cleaner column filters; and experience a refreshed, responsive login screen with consistent branded loaders during navigation.

• Rich-text email composer: New src/components/ui/rich-text-editor.tsx wrapping CKEditor 5; ShareViaMailDialog now uses it instead of a contentEditable div, with email-body validation. Adds @ckeditor/ckeditor5-react + react-icons deps and transpilePackages: ["ckeditor5"] in next.config.ts (PR #376).
• Sync to Payments (PTP): Single and bulk sync surfaced in MailDocuments.tsx with a sync icon and "Synced by {name}" tooltip; ptp.mutation.ts bulk hook now invalidates the mailDetails query cache after success (PRs #368, #375).
• PDF viewer: PDFControls, PDFViewerCore, usePDFState reworked for inline -/100%/+ zoom (25%-300%), fit-to-width, orientation toggle, corrected page-nav icons, tooltips and aria-labels; viewer is dynamically imported in mail/document detail pages (PRs #369, #380).
• Data grids: New truncated-text.tsx + useTruncateText for tooltip-on-truncate; debounced column-filter search; "N/A" shown for empty filter values; duplicate filter labels removed (PRs #364, #365, #367, #372).
• Auth & shell: Redesigned responsive login page; new src/app/auth/redirect/page.tsx that waits for permissions before routing to /inbox; new BrandedLoader and route-level loading.tsx files unifying loading UI (PRs #379, #381, #382, #383, #385).
• API URL standardization: Trailing slashes added to ~150 route definitions across 29 files in src/routes/ (query-string routes left unchanged) (PR #373).
• Mail/Document detail tab state moved to URL search params; batch/mail/document add-and-edit modal UI refinements.

Risk is moderate due to the breadth of changes (93 files, ~4,990 additions). The trailing-slash route change touches nearly every API call and could break any endpoint that does not tolerate a trailing slash; CKEditor adds a sizable client bundle and requires correct transpilation. Mitigation: changes are landing in QA (not production) for validation, query-string routes were deliberately excluded, the PDF viewer is dynamically imported to limit blast radius, and PTP bulk sync now invalidates cached mail details to avoid stale UI.

• Compose and send a shared email via the rich-text editor; verify formatting (bold/lists/headings/colors/image), required-body validation, and delivered content.
• Sync documents to PTP from the mail Documents tab, single and bulk; confirm success toast, the "Synced by" indicator, and that mail details refresh without manual reload.
• Exercise the PDF viewer: zoom in/out and exact %, fit-to-width, rotate/orientation, page navigation, tooltips, and keyboard/screen-reader labels.
• Verify grid column filters: debounced search, empty values shown as "N/A", no duplicate filter labels; confirm long cell values truncate with a hover tooltip.
• Smoke-test login and the new post-login redirect (permissions load before landing on Inbox; error path returns to login) and confirm branded loaders appear on slow navigations.
• Regression-check core API calls across modules (mails, documents, batches, folders, resolution) to ensure trailing-slash URLs return data with no broken requests or redirect loops.