Save active sessions in browser local storage

Joining a game now records the session (game ID, player ID, plus
player/rat/crew names) in localStorage via the new lib/sessions.js, and
the dashboard keeps it enriched as state loads (so the rat name tracks
earned Names). The home page lists saved sessions in a "Rejoin a Crew"
menu, most-recent first, alongside creating a new game.

Deleting an entry only touches localStorage, never the backend, and is
undoable: the row greys out with an Undo button and is dropped from
storage immediately, so a page refresh finalizes the removal.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/pages/Dashboard.svelte

@@ -5,6 +5,7 @@
     import { getSuggestion } from '../lib/suggestions';
     import { displayName } from '../lib/cards';
     import { setPageTitle } from '../lib/title';
+    import { saveSession } from '../lib/sessions';
 
     import LobbyPhase from '../components/LobbyPhase.svelte';
     import CharacterCreationPhase from '../components/CharacterCreationPhase.svelte';
@@ -108,6 +109,18 @@
     // Distinguish tabs/history by the Pi-Rat (and crew) this dashboard is for
     $: setPageTitle(state ? displayName(state.player) : null, state?.game?.crew_name);
 
+    // Keep this browser's saved session up to date so the home page can rejoin
+    // with current crew/rat names (the rat name changes when a Name is earned)
+    $: if (state?.game && state?.player) {
+        saveSession({
+            gameId,
+            playerId,
+            crewName: state.game.crew_name,
+            playerName: state.player.player_name,
+            ratName: state.player.name,
+        });
+    }
+
     // Admins get the admin key in their state blob; stash it so the Admin page works for them too
     $: if (state?.player?.is_admin && state?.game?.admin_key) {
         localStorage.setItem(`admin_key_${gameId}`, state.game.admin_key);