Refactor: unify dialog styles across components

- Add unified .dialog-overlay and .dialog classes to tailwind.css
- Remove duplicated dialog styles from 9 Vue components
- Standardize z-index to 50 for all dialogs
- Preserve special cases: FeedFilters (z-index: 100), PhotoDialog (camera styles)
- Eliminate ~200 lines of duplicated CSS code
- Updated ContactNameDialog from using getter methods to direct CSS classes
- Improve maintainability with single source of truth for dialog styling

src/components/ImageMethodDialog.vue

@@ -931,32 +931,6 @@ export default class ImageMethodDialog extends Vue {
 </script>
 
 <style>
-.dialog-overlay {
-  z-index: 50;
-  position: fixed;
-  top: 0;
-  left: 0;
-  right: 0;
-  bottom: 0;
-  background-color: rgba(0, 0, 0, 0.5);
-  display: flex;
-  justify-content: center;
-  align-items: center;
-  padding: 1.5rem;
-}
-
-.dialog {
-  background-color: white;
-  padding: 1rem;
-  border-radius: 0.5rem;
-  width: 100%;
-  max-width: 700px;
-  max-height: 90vh;
-  overflow: hidden;
-  display: flex;
-  flex-direction: column;
-}
-
 /* Add styles for diagnostic panel */
 .diagnostic-panel {
   font-family: monospace;