fix(ui): Prevent Enter key from triggering submission on mobile devices (#3970)

- Add check for mobile screen width (<= 768px) to prevent accidental submissions via the Enter key.
- Update event listeners in static/app.js and static/js/chat.js to respect this constraint.

static/app.js

@@ -3135,7 +3135,9 @@ function initializeEventListeners() {
       setTimeout(() => uiModule.autoResize(textarea), 1);
     });
     textarea.addEventListener('keydown', (e) => {
-      if (e.key === 'Enter' && !e.shiftKey && !e.isComposing) {
+      const isMobile = window.innerWidth <= 768
+
+      if (e.key === 'Enter' && !e.shiftKey && !e.isComposing && !isMobile) {
         // If ghost autocomplete is active, accept the suggestion instead of submitting
         if (window._ghostAutocomplete && window._ghostAutocomplete.isActive()) {
           e.preventDefault();
@@ -3708,7 +3710,9 @@ function startOdysseusApp() {
   // Enter to send (shift+enter for newline), or new chat when empty
   if (messageInput) {
     messageInput.addEventListener('keydown', (e) => {
-      if (e.key === 'Enter' && !e.shiftKey && !e.isComposing) {
+      const isMobile = window.innerWidth <= 768
+
+      if (e.key === 'Enter' && !e.shiftKey && !e.isComposing && !isMobile) {
         e.preventDefault();
         // Flush the debounced icon update so dataset.mode reflects the current
         // text state. Without this, a fast type-and-Enter would still see the

static/js/chat.js

@@ -3868,7 +3868,9 @@ import { wireArrowUpRecall, getLastUserMessageFromChatHistory } from './composer
 
     // Also submit on Enter (without shift)
     editor.addEventListener('keydown', (e) => {
-      if (e.key === 'Enter' && !e.shiftKey && !e.isComposing) {
+      const isMobile = window.innerWidth <= 768
+
+      if (e.key === 'Enter' && !e.shiftKey && !e.isComposing && !isMobile) {
         e.preventDefault();
         saveBtn.click();
       }