chore: improve reaction picker behaviour

src/client/components/emoji-picker-dialog.vue

 <template>
-<MkModal ref="modal" :manual-showing="manualShowing" :src="src" @click="$refs.modal.close()" @opening="$refs.picker.focus()" @close="$emit('close')" @closed="$emit('closed')">
+<MkModal ref="modal" :manual-showing="manualShowing" :src="src" @click="$refs.modal.close()" @opening="opening" @close="$emit('close')" @closed="$emit('closed')">
 	<MkEmojiPicker :show-pinned="showPinned" :as-reaction-picker="asReactionPicker" @chosen="chosen" ref="picker"/>
 </MkModal>
 </template>
@@ -46,6 +46,11 @@ export default defineComponent({
 			this.$emit('done', emoji);
 			this.$refs.modal.close();
 		},
+
+		opening() {
+			this.$refs.picker.reset();
+			this.$refs.picker.focus();
+		}
 	}
 });
 </script>

src/client/components/emoji-picker.vue

@@ -282,6 +282,10 @@ export default defineComponent({
 			}
 		},
 
+		reset() {
+			this.$refs.emojis.scrollTop = 0;
+		},
+
 		getKey(emoji: any) {
 			return typeof emoji === 'string' ? emoji : (emoji.char || `:${emoji.name}:`);
 		},