feat: move voice enable/model config to admin UI

Replace VOICE_ENABLED env var gate with DB-backed admin setting.

- services/voice_config.py: reads voice_enabled + voice_stt_model from
  admin user's settings row (falls back to env var defaults)
- routes/admin.py: GET/PUT /api/admin/voice for admin configuration
- routes/voice.py, services/stt.py, services/tts.py: read enabled/model
  from DB via voice_config instead of Config directly
- app.py: always schedule model loaders at startup; they self-gate on
  the DB setting so no conditional needed at the call site
- SettingsView.vue: Voice section in Admin → Config tab (enable toggle +
  STT model dropdown); user Voice tab now points to admin panel when disabled

No env var required to test — enable via Settings → Admin → Config → Voice.

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

frontend/src/views/SettingsView.vue

@@ -445,6 +445,29 @@ const baseUrl = ref("");
 const savingBaseUrl = ref(false);
 const baseUrlSaved = ref(false);
 
+// Voice config (admin only)
+const adminVoiceEnabled = ref(false);
+const adminVoiceSttModel = ref("base.en");
+const savingAdminVoice = ref(false);
+const adminVoiceSaved = ref(false);
+
+async function saveAdminVoice() {
+  savingAdminVoice.value = true;
+  adminVoiceSaved.value = false;
+  try {
+    await apiPut("/api/admin/voice", {
+      voice_enabled: adminVoiceEnabled.value,
+      voice_stt_model: adminVoiceSttModel.value,
+    });
+    adminVoiceSaved.value = true;
+    setTimeout(() => { adminVoiceSaved.value = false; }, 2000);
+    // Refresh the user-facing voice status after toggling
+    voiceTabLoaded.value = false;
+  } finally {
+    savingAdminVoice.value = false;
+  }
+}
+
 // Search test (SearXNG)
 const searxngConfigured = ref(false);
 const searxngUrl = ref("");
@@ -565,6 +588,13 @@ onMounted(async () => {
     } catch {
       // base URL not configured yet
     }
+    try {
+      const vc = await apiGet<Record<string, string>>("/api/admin/voice");
+      adminVoiceEnabled.value = vc.voice_enabled === "true";
+      adminVoiceSttModel.value = vc.voice_stt_model ?? "base.en";
+    } catch {
+      // voice not configured yet
+    }
   }
   _loadTabContent(activeTab.value);
 });
@@ -1888,9 +1918,8 @@ function formatUserDate(iso: string): string {
         </div>
 
         <div v-if="!voiceStatus?.enabled" class="field-hint" style="margin-top:0.75rem;">
-          Set <code>VOICE_ENABLED=true</code> in your server environment to activate voice features.
-          Optionally set <code>STT_MODEL</code> (tiny.en / base.en / small.en / medium.en) and
-          install <code>pip install fabledassistant[voice]</code>.
+          Voice is disabled. An administrator can enable it under
+          <strong>Admin → Config → Voice</strong>.
         </div>
       </section>
 
@@ -2146,6 +2175,38 @@ FABLE_API_KEY=&lt;your-api-key&gt;</pre>
         </div>
       </section>
 
+      <section class="settings-section full-width">
+        <h2>Voice (Speech-to-Speech)</h2>
+        <p class="section-desc">
+          Enable self-hosted voice using faster-whisper (STT) and Kokoro (TTS).
+          Models load at startup — a server restart is required after changing these settings.
+          Install dependencies first: <code>pip install faster-whisper kokoro soundfile</code>
+        </p>
+        <div class="checkbox-field">
+          <label>
+            <input type="checkbox" v-model="adminVoiceEnabled" />
+            Enable Voice
+          </label>
+          <p class="field-hint">Shows the PTT button and voice settings to all users.</p>
+        </div>
+        <div v-if="adminVoiceEnabled" class="field" style="max-width:280px; margin-top:0.75rem;">
+          <label for="stt-model">STT Model</label>
+          <select id="stt-model" v-model="adminVoiceSttModel" class="input">
+            <option value="tiny.en">tiny.en — fastest, lowest accuracy (~75 MB)</option>
+            <option value="base.en">base.en — balanced (recommended, ~145 MB)</option>
+            <option value="small.en">small.en — better accuracy (~465 MB)</option>
+            <option value="medium.en">medium.en — best accuracy (~1.5 GB)</option>
+          </select>
+          <p class="field-hint">Larger models are more accurate but use more RAM and take longer to load.</p>
+        </div>
+        <div class="actions" style="margin-top:0.85rem;">
+          <button class="btn-save" @click="saveAdminVoice" :disabled="savingAdminVoice">
+            {{ adminVoiceSaved ? 'Saved ✓' : savingAdminVoice ? 'Saving…' : 'Save' }}
+          </button>
+          <span v-if="adminVoiceSaved" class="field-hint">Restart the server to apply model changes.</span>
+        </div>
+      </section>
+
     </div>
 
     <!-- ── Users ── -->