QA Build (7 Oct 2025): Mail Sharing Attachments, Cleaner Mail & Document Screens, and a Codebase Hardening Pass

This QA build bundles several merged changes (PRs #495, #496, #467, #498, #499, #497). The headline user-facing addition is file attachment support when sharing mail externally by email. It also tidies up the mail and document detail screens, fixes data-grid filter/search resets when switching status, and includes a large internal type-safety and dead-code cleanup that improves stability without changing behavior.

Two needs drove this build. First, users sharing mail outside the system by email could not include file attachments — the capability existed only as disabled, commented-out code. Second, the codebase had accumulated loose typing (any), disabled lint rules, dead pages, and unfinished UI (e.g. a non-functional inline "Edit Details / Save Changes" control on the mail detail screen). Cleaning these up reduces the chance of silent runtime errors and removes confusing half-built controls before they reach users.

• Users can now attach files when sharing mail externally via email, with file-type icons, attachment badges, and a remove control.
• The data grid more reliably clears filters and search text when the status changes, so stale filters no longer hide results.
• The mail detail screen no longer shows a non-working inline "Edit Details / Save Changes" control, and the organization switcher now shows subclient and client name for clearer context.
• Most changes are internal hardening; end users should see steadier behavior and fewer edge-case errors rather than new screens.

• Mail sharing attachments (PR #499 / feat-mail-details-bonus): activated the previously commented-out attachment block in ShareViaMailDialog.tsx, wiring in Paperclip/Image/File icons, attachment badges, and remove (X) actions.
• Mail & document detail cleanup: removed the unfinished inline edit/save UI from batches/mails/[id]/page.tsx; deleted the legacy 938-line (dashboard)/mails/page.tsx grid and dropped MailContextProvider from the mails layout; converted the document viewer's idle-preload from any-typed requestIdleCallback shims to typed fallbacks.
• Add Mail / Address Manager refactor: exported typed option models (ContactOption, DepartmentOption, OrganizationOption, SenderOrRecipientDetails) from MailForm, added safe option normalization in AddMailsModal, rebuilt AddressManager with typed address records, and threaded an isEditing prop through MailOverview.
• Data grid filter reset (PR #497): added a resetOnStatusChange prop (clearFilters / clearSearch) to data-grid.tsx and stabilized grid search-reset handling.
• Comments system (PR #498): tooltip for deleted users, hardened mention handling, and removed any across CommentsDrawer, ThreadView, MessageBubble, and mention utilities.
• Type-safety / lint pass (PRs #496, #467): removed any and eslint-disable headers across auth, dashboard, admin hub, column filters, export modal, and rich-text editor; swapped <img> for next/image in FilePreview; deleted dead src/actions/auth-action.ts.
• Docs/config (PR #495): added coding rules to AGENTS.md (no hard-coded values, mandatory pnpm lint, ban on any), added CLAUDE.md/GEMINI.md symlinks, and moved BROWSER_NOTIFICATIONS.md into ai_docs/.

Moderate breadth, low-to-moderate risk. The change touches ~100 files (2,574 additions / 4,344 deletions), but the bulk is type tightening and dead-code removal rather than new logic. Main risks: (1) deleting the standalone /mails grid page and the mail context could break any lingering links or shared state that depended on them; (2) the new resetOnStatusChange grid behavior could over-clear or under-clear filters in unexpected views; (3) the newly enabled attachment flow is brand-new functionality and needs end-to-end validation. Mitigation: this reached the QA branch (not Production) specifically so these paths can be exercised before promotion.

• Mail external share: open Share via Email, add and remove attachments, verify icons/badges render and the email sends successfully with attachments.
• Data grids: switch status filters on mail/batch/document grids and confirm filters and search clear correctly and results refresh.
• Mail detail screen: confirm the old inline "Edit Details / Save Changes" control is gone and the overview/resolution tabs still work.
• Add Mail / Address Manager: create a mail, select organizations/departments/contacts as sender and recipient, and confirm options load and save without errors.
• Comments: verify mentions still resolve, deleted-user comments show a tooltip, and threads render.
• Regression sweep: smoke-test login/auth, dashboard notifications, document viewer/file preview, and the organization switcher (subclient + client name display).