feat: add message editing

This commit adds message editing as a feature. To accomplish this, the settings
dialog was refactored into a singleton and now the message edit and settings
use the singleton where appropriate.

app/components/Message/index.vue

@@ -1,7 +1,9 @@
 <script setup lang="ts">
 import type { Message } from '~/composables/useChat';
+import { assert } from '~~/utils/assert';
 
 const triplit = useTriplitClient();
+const { openDialog } = useDialog();
 
 const { message } = defineProps<{
     message: Message
@@ -88,6 +90,26 @@ const regenerateMessage = async () => {
     emit('regenerate');
 }
 
+const handleEdit = async () => {
+    openDialog<string>(DialogType.Textbox, async (res) => {
+        if (res.ok) {
+            if (!res.data) return;
+
+            await triplit.update('messages', message.id, {
+                content: res.data
+            });
+
+            assert('flush' in triplit);
+            await triplit.flush();
+
+            await regenerateMessage();
+        }
+    }, {
+        title: 'Edit Message',
+        initialValue: message.content
+    });
+};
+
 const deleteMessage = () => {
     if (focusedIndex.value !== 0 && focusedIndex.value === message.children.length) {
         focusedIndex.value = Math.max(0, focusedIndex.value - 1);
@@ -135,6 +157,10 @@ const messageCount = computed(() => {
                     class="flex justify-center items-center w-7 h-6 hover:bg-[var(--color-hover)]">
                     <Icon name="mynaui:refresh" class="text-4.5" />
                 </button>
+                <button v-if="message.role === 'user'" @click="handleEdit"
+                    class="flex justify-center items-center w-7 h-6 hover:bg-[var(--color-hover)]">
+                    <Icon name="mynaui:pencil" class="text-4.5" />
+                </button>
                 <button @click="copyMessage" :class="{ 'text-emerald-500': copied }"
                     class="flex justify-center items-center w-7 h-6 hover:bg-[var(--color-hover)]">
                     <Icon :name="copied ? 'mynaui:check' : 'mynaui:copy'" class="text-4.5" />