rename: the sign-in screen shows Inkwell's mark, and every tab says Inkwell

The login and register screens still drew a hard-coded "TS" tile. They now
use /icon.svg, the same mark the shell's header shows.

Browser tabs took index.html's static <title> and never changed it, so every
tab read the same, and some browsers showed the URL instead. usePageTitle,
mounted once in App.vue, sets "<page> · <site name>". Routes outside the shell
name themselves with meta.title. Board lenses use the lens name the header
already shows, now in useLensName so the tab and the header read from one
place.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/router/index.ts

@@ -31,13 +31,13 @@ const router = createRouter({
       path: "/capture",
       name: "capture",
       component: () => import("../views/CaptureView.vue"),
-      meta: { requiresAuth: true, requiresDesktop: true },
+      meta: { title: "Quick capture", requiresAuth: true, requiresDesktop: true },
     },
     {
       path: "/settings",
       name: "settings",
       component: () => import("../views/SettingsView.vue"),
-      meta: { requiresAuth: true, requiresAdmin: true },
+      meta: { title: "Settings", requiresAuth: true, requiresAdmin: true },
     },
     {
       // Desktop only: connect this app to a server. Meaningless in the web build,
@@ -45,7 +45,7 @@ const router = createRouter({
       path: "/sync",
       name: "sync",
       component: () => import("../views/SyncView.vue"),
-      meta: { requiresAuth: true, requiresDesktop: true },
+      meta: { title: "Sync", requiresAuth: true, requiresDesktop: true },
     },
     {
       // Per-user account: linked devices (native-client sync tokens). Any user.
@@ -58,19 +58,19 @@ const router = createRouter({
       path: "/account",
       name: "account",
       component: () => import("../views/AccountView.vue"),
-      meta: { requiresAuth: true, requiresServer: true },
+      meta: { title: "Linked devices", requiresAuth: true, requiresServer: true },
     },
     {
       path: "/login",
       name: "login",
       component: () => import("../views/LoginView.vue"),
-      meta: { guestOnly: true },
+      meta: { title: "Sign in", guestOnly: true },
     },
     {
       path: "/register",
       name: "register",
       component: () => import("../views/RegisterView.vue"),
-      meta: { guestOnly: true },
+      meta: { title: "Create account", guestOnly: true },
     },
   ],
 });