v3.2.6-sr94.22: Keyboard, focus and pagination reliability

Keyboard And Focus Reliability

• Give the shortener, personal/admin action buttons, filters and pagination meaningful accessible names and visible keyboard focus.
• Use native admin tabs with selected state and keyboard navigation. Calculate Next-page availability from the actual result count, including empty and last pages.
• Preserve focus across asynchronous saves, replacement forms and management navigation without stealing focus from a newer draft.
• Initialize inserted HTMX editors immediately; make their native fallback POST-only so fast keyboard submissions cannot place fields in a GET URL.
• Keep authentication, authorization, public redirects, API contracts and database schema unchanged.

Automated rendered-control, pagination, focus-lifecycle and full isolated regression tests accompany the changes. Desktop and 390/320px browser workflows passed in disposable fixtures. Production acceptance remains gated on exact hardened-image, backup/restore and deployed-service tests recorded in docs/UI-UX-REVIEW.md.

Known separate findings, including narrow admin-table clipping and content-heading overlap, remain open. This is not a claim that the entire UI/UX review is complete.