feat: add Send and Received tabs to Formgent enquiries

[nazmulhasan103]

Summary

• Add Received and Send tabs inside the existing Directorist dashboard Enquiries view. https://prnt.sc/lWsmg3z0ZhtV
• Received lists completed Formgent submissions for listings owned by the current user; Send lists completed listing submissions created by the current user.
• Reuse the existing response records and submitter identity. No database migration or Formgent plugin changes are required.

Workflow And Permissions

• Keep received-item read/delete actions restricted to listing owners. Send details are read-only and opening them does not mark the owner's enquiry as read.
• Apply the selected scope consistently to lists, details, and KPI counts, with server-side pagination and search. Search matches senders in Received and recipients in Send.
• Preserve Received as the default for existing API callers. Include non-trashed expired listings; exclude incomplete/draft responses and non-listing forms. Guest submissions remain visible to recipients but are not attributed to an authenticated sender.
• Add a circular tab-switch loader with reduced-motion support, responsive table/list layouts, and refresh on dashboard focus/visibility changes.
• Preserve search focus and open details during background refreshes, including automatic received-item read updates.

Validation

• Local WP-CLI regression checks passed during development for user scopes, guests, self-submissions, pagination, search, KPIs, excluded records, and owner-only read/delete permissions. These checks failed on the unchanged development baseline.
• Production Webpack build of the Formgent integration entry passed. Only bundle-size warnings remain.
• PHPCS passed for the changed PHP files using the repository's PR-check configuration.
• Prettier passed for all five modified JavaScript source files; git diff whitespace check passed.
• Local browser checks passed at 1440px and 390px: tab-switch spinner, reduced motion, Send read-only details, search focus, focus refresh, Received modal persistence after read refresh, and no horizontal page overflow.

Scope

Targets sovware/directorist:development from nazmulhasan103:codex/enquiries-send-received. Includes only the dashboard integration, scoped API changes, localized strings, and compiled integration JavaScript. No test files, site-specific candidate form configuration, release ZIPs, database migrations, or Formgent plugin changes are included.