Mail Details: Accurate document-type display and safer in-form buttons

The mail detail view now pulls the list and count of document types from a dedicated, freshly-fetched source instead of relying on data embedded in the mail record, so the "Document Type" section stays accurate after a quick upload. Several icon buttons across pagination and the user/folder assignment screens were also hardened so they no longer accidentally submit the surrounding form. This change has reached the QA/testing environment.

On the mail details screen, the document-type list and its count were read from fields baked into the mail object (mail.document_types / mail.document_count). After a user quick-uploaded a document, these embedded fields could be stale, so the count and badges shown to the user did not always reflect reality. Separately, icon-only action buttons (pagination arrows, assign/unassign controls) had no explicit button type; inside a form a button defaults to submit, which can trigger an unintended form submission or page action when clicked.

Users viewing a mail in the batches workflow now see a correct, up-to-date document-type count and badge list, with a brief loading placeholder while it fetches. Adding a document via quick upload reliably refreshes that section. Clicking pagination or assign/unassign arrows no longer risks an accidental form submission, making the Folders and Organization assignment steps and the folder pagination behave more predictably.

• MailOverviewDetails.tsx: replaces the embedded mail.document_types / mail.document_count with the useGetDocumentTypeByMailId(mail.mail_id) query; renders count from documentTypeData.count, badges from documentTypeData.items (keyed by id/name), and shows a Skeleton while loading.
• documentType.queries.ts: useGetDocumentTypeByMailId now unwraps the service response, returning result.data on success and null otherwise.
• document.mutations.ts: the quick-upload success handler now invalidates only the document_type_by_mail_id query key instead of a broad set of keys (mailDetails, documentsGrid, documentDetails, documentStatus, documentTypes, document_type_paginated).
• QuickDocumentUpload.tsx: adds the useQueryClient hook/import.
• Pagination.tsx, AssignUsersStep.tsx, AssignFoldersStep.tsx: add type="button" to icon buttons; minor let->const and JSX whitespace cleanup in pagination.
• Net change is small (+43 / -16 across 7 files).

Low overall. Main behavioral risk: the document-type section now depends on a separate fetch, so the displayed list/count is only as current as that query. The narrowed cache invalidation on quick upload means any view previously relying on the broader invalidation (e.g. documents grid) could miss a refresh; this is mitigated because the only changed surface is the per-mail document-type section, which targets the correct key. The type="button" additions are non-functional safety changes with negligible risk.

• Open a mail in the batches workflow with zero document types: confirm the quick-upload form appears and a skeleton shows briefly while loading.
• Open a mail with one or more document types: verify the count in the "Document Type" header and the badges match the actual document types.
• Quick-upload a document, then confirm the count and badge list update without a manual refresh.
• In Folders pagination and the Assign Users / Assign Folders steps, click the arrow and chevron buttons and confirm they only paginate/assign and never submit or reset the surrounding form.
• Verify disabled states on the assign/unassign and prev/next buttons still behave correctly.