feat: App mode saving rework (#9338)

## Summary

Change app mode changes to be written directly to the workflow on change
instead of requiring explicit save via builder.
Temporary: Adds `.app.json` file extension to app files for
identification since we don't currently have a way to identify them with
metadata
Removes app builder save dialog and replaces it with default mode
selection

## Changes

- **What**: 
- ensure all save locations handle app mode
- remove dirtyLinearData and flushing

- **Breaking**: 
- if people are relying on workflow names and are converting to/from app
mode in the same workflow, they will gain/lose the `.app` part of the
extension

## Screenshots (if applicable)

<img width="689" height="84" alt="image"
src="https://github.com/user-attachments/assets/335596ee-dce9-4e3a-a7b5-f0715c294e41"
/>

<img width="421" height="324" alt="image"
src="https://github.com/user-attachments/assets/ad3cd33c-e9f0-4c30-8874-d4507892fc6b"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9338-feat-App-mode-saving-rework-3176d73d3650813f9ae1f6c5a234da8c)
by [Unito](https://www.unito.io)

src/components/builder/DefaultViewDialogContent.vue

@@ -0,0 +1,97 @@
+<template>
+  <BuilderDialog @close="$emit('close')">
+    <template #title>
+      {{ $t('builderToolbar.defaultViewTitle') }}
+    </template>
+
+    <div class="flex flex-col gap-2">
+      <label class="text-sm text-muted-foreground">
+        {{ $t('builderToolbar.defaultViewLabel') }}
+      </label>
+      <div role="radiogroup" class="flex flex-col gap-2">
+        <Button
+          v-for="option in viewTypeOptions"
+          :key="option.value.toString()"
+          role="radio"
+          :aria-checked="openAsApp === option.value"
+          :class="
+            cn(
+              itemClasses,
+              openAsApp === option.value && 'bg-secondary-background'
+            )
+          "
+          variant="textonly"
+          @click="openAsApp = option.value"
+        >
+          <div
+            class="flex size-8 min-h-8 items-center justify-center rounded-lg bg-secondary-background-hover"
+          >
+            <i :class="cn(option.icon, 'size-4')" />
+          </div>
+          <div class="mx-2 flex flex-1 flex-col items-start">
+            <span class="text-sm font-medium text-base-foreground">
+              {{ option.title }}
+            </span>
+            <span class="text-xs text-muted-foreground">
+              {{ option.subtitle }}
+            </span>
+          </div>
+          <i
+            v-if="openAsApp === option.value"
+            class="icon-[lucide--check] size-4 text-base-foreground"
+          />
+        </Button>
+      </div>
+    </div>
+
+    <template #footer>
+      <Button variant="muted-textonly" size="lg" @click="$emit('close')">
+        {{ $t('g.cancel') }}
+      </Button>
+      <Button variant="secondary" size="lg" @click="$emit('apply', openAsApp)">
+        {{ $t('g.apply') }}
+      </Button>
+    </template>
+  </BuilderDialog>
+</template>
+
+<script setup lang="ts">
+import { ref } from 'vue'
+import { useI18n } from 'vue-i18n'
+
+import Button from '@/components/ui/button/Button.vue'
+import { cn } from '@/utils/tailwindUtil'
+
+import BuilderDialog from './BuilderDialog.vue'
+
+const { t } = useI18n()
+
+const { initialOpenAsApp = true } = defineProps<{
+  initialOpenAsApp?: boolean
+}>()
+
+defineEmits<{
+  apply: [openAsApp: boolean]
+  close: []
+}>()
+
+const openAsApp = ref(initialOpenAsApp)
+
+const viewTypeOptions = [
+  {
+    value: true,
+    icon: 'icon-[lucide--app-window]',
+    title: t('builderToolbar.app'),
+    subtitle: t('builderToolbar.appDescription')
+  },
+  {
+    value: false,
+    icon: 'icon-[comfy--workflow]',
+    title: t('builderToolbar.nodeGraph'),
+    subtitle: t('builderToolbar.nodeGraphDescription')
+  }
+]
+
+const itemClasses =
+  'flex h-14 cursor-pointer items-center gap-2 self-stretch rounded-lg border-none bg-transparent py-2 pr-4 pl-2 text-base-foreground transition-colors hover:bg-secondary-background'
+</script>