feat(toolbar): make themes always visible, view groups conditional

Themes are a global preference — always shown when logged in.
Connection, quad-view, and panels remain view-specific via provideToolbar.
Fixes blank toolbar when navigating to views that don't call provideToolbar.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/AppToolbar.vue

@@ -1,5 +1,5 @@
 <template>
-    <div v-if="isLoggedIn && toolbar" class="app-toolbar">
+    <div v-if="isLoggedIn" class="app-toolbar">
 
         <!-- Group: Connection + Takeover (only if view provides a connection) -->
         <div v-if="conn" class="toolbar-group">
@@ -31,7 +31,7 @@
         </div>
 
         <!-- Group: Themes -->
-        <div v-if="hasGroup('themes')" class="toolbar-group">
+        <div class="toolbar-group">
             <button v-for="t in THEMES" :key="t" class="toolbar-btn" :class="{ active: theme === t }" @click="setTheme(t)" :title="THEME_NAMES[t]">
                 <component :is="THEME_ICONS[t]" class="w-6 h-6" />
             </button>