feat: add keyboard shortcut Cmd/Ctrl+S to SaveButton

- Add Cmd+S (Mac) or Ctrl+S (Windows/Linux) keyboard shortcut to save CSS
- Detect platform to display correct shortcut symbol (⌘ or Ctrl)
- Prevent default browser save behavior
- Translate tooltips to French
- Show shortcut in button tooltip

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/components/SaveButton.vue

@@ -39,7 +39,7 @@
 </template>
 
 <script setup>
-import { ref, computed } from 'vue';
+import { ref, computed, onMounted, onUnmounted } from 'vue';
 import { useStylesheetStore } from '../stores/stylesheet';
 
 const stylesheetStore = useStylesheetStore();
@@ -51,6 +51,10 @@ const lastSavedFormatted = computed(() => stylesheetStore.lastSavedFormatted);
 const hasError = computed(() => !!saveError.value);
 const showSuccess = ref(false);
 
+// Detect platform for keyboard shortcut display
+const isMac = typeof navigator !== 'undefined' && navigator.platform.toUpperCase().indexOf('MAC') >= 0;
+const shortcutKey = isMac ? '⌘' : 'Ctrl';
+
 const handleSave = async () => {
   const result = await stylesheetStore.saveCustomCss();
 
@@ -64,12 +68,34 @@ const handleSave = async () => {
   // Errors are handled in the store and reflected in hasError
 };
 
-const getTooltip = () => {
-  if (!isDirty.value) return 'No changes to save';
-  if (isSaving.value) return 'Saving...';
-  if (hasError.value) return saveError.value;
-  return 'Save custom CSS';
+const handleKeyDown = (event) => {
+  // Check for Cmd+S (Mac) or Ctrl+S (Windows/Linux)
+  if ((event.metaKey || event.ctrlKey) && event.key === 's') {
+    event.preventDefault();
+
+    // Only save if there are changes and not currently saving
+    if (isDirty.value && !isSaving.value) {
+      handleSave();
+    }
+  }
 };
+
+const getTooltip = () => {
+  if (!isDirty.value) return 'Aucune modification à enregistrer';
+  if (isSaving.value) return 'Enregistrement...';
+  if (hasError.value) return saveError.value;
+  return `Enregistrer le CSS personnalisé (${shortcutKey}+S)`;
+};
+
+// Add keyboard listener on mount
+onMounted(() => {
+  window.addEventListener('keydown', handleKeyDown);
+});
+
+// Remove keyboard listener on unmount
+onUnmounted(() => {
+  window.removeEventListener('keydown', handleKeyDown);
+});
 </script>
 
 <style scoped>