Inbox/auth/operator UX polish release train.
- Added the 1024px chat-pane background tile for light-mode inbox threads, encoded as a compact WebP and disabled in dark mode until a native dark asset exists.
- Added Switchbord wordmarks inside sign-in and sign-up cards.
- After successful sign-up, the form now locks, shows an emerald success callout, and redirects to sign-in after one second.
- Replaced “MSN-style” notification language with desktop notification language and uses browser system notifications for off-window inbound messages, with the in-app popup as fallback.
- Improved the inbox assignment picker so it grows up to 15 operators, remains searchable/scrollable for larger teams, and highlights assigned operators with an emerald rail/fill.
- Resolved internal note author UUIDs to workspace member display names when profile fields are available.
- Enlarged the sidebar wordmark by 20% and switched active nav rows to an emerald-tinted highlight while keeping the left rail.