refactor: Improve voice and response modals UX

- Center both modals with dark backdrop and blur effect
- Make voice modal larger (420px) with bigger record button
- Make response modal larger (540px) with bigger text (18px)
- Remove auto-dismiss from bubbles - manual dismiss only
- Add backdrop click to close response modal
- Remove unused bottom sheet code from FloatingVoice
- Add touch protection CSS to prevent text selection
- Clean up mobile-specific variables no longer needed

frontend/src/App.vue

@@ -308,9 +308,6 @@ onMounted(async () => {
     },
     getMessages: () => {
       return responseRef.value?.getMessages() || []
-    },
-    move: (x: number, y: number) => {
-      responseRef.value?.move(x, y)
     }
   })
 
@@ -624,6 +621,11 @@ watch(() => route.name, (newPage) => {
   z-index: 9998;
   overflow: visible;
   backdrop-filter: blur(10px);
+  /* Prevent text selection and touch gestures */
+  -webkit-user-select: none;
+  user-select: none;
+  -webkit-touch-callout: none;
+  touch-action: manipulation;
 }
 
 .terminal-fab::before {
@@ -976,6 +978,11 @@ watch(() => route.name, (newPage) => {
   box-shadow: 0 6px 20px rgba(16, 185, 129, 0.4);
   transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
   z-index: 9998;
+  /* Prevent text selection and touch gestures */
+  -webkit-user-select: none;
+  user-select: none;
+  -webkit-touch-callout: none;
+  touch-action: manipulation;
 }
 
 .voice-fab:hover {