fix: drop phantom ended-tab stubs, trust server as source of truth (#93)

Previously the client cached open session tabs in localStorage and resurrected
any that the server no longer knew about as grayed-out "ended" stubs. On
multi-device use (close tab on mobile, open desktop) this left stale phantom
tabs the user had to manually dismiss.

Remove _restoreEndedTabs / _saveTabMetadata, the session._ended branch in
selectSession, the data-ended render attribute, and the matching CSS rule.
Clear the legacy localStorage key on init to purge stale entries.

Co-authored-by: Teigen <teigen@TeigendeMac-mini.local>

src/web/public/terminal-ui.js

@@ -444,7 +444,6 @@ Object.assign(CodemanApp.prototype, {
             if (
               activeResizeSession &&
               activeResizeSession.mode !== 'shell' &&
-              !activeResizeSession._ended &&
               this.terminal &&
               this.isTerminalAtBottom()
             ) {