App builder exit updates (#9218)

## Summary

- remove exit builder button from right panel
- add builder exit button to bottom of canvas
- add builder menu with save & exit in top left

## Screenshots (if applicable)

<img width="1544" height="998" alt="image"
src="https://github.com/user-attachments/assets/f5deadc5-2bf5-4729-b644-2b6a815b9975"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9218-App-builder-exit-updates-3126d73d365081a0bf1adf92e1171060)
by [Unito](https://www.unito.io)

src/components/builder/BuilderMenu.vue

@@ -0,0 +1,73 @@
+<template>
+  <Popover :show-arrow="false" class="min-w-56 p-3">
+    <template #button>
+      <button
+        :class="
+          cn(
+            'absolute left-4 top-[calc(var(--workflow-tabs-height)+16px)] z-1000 inline-flex h-10 cursor-pointer items-center gap-2.5 rounded-lg py-2 pr-2 pl-3 shadow-interface transition-colors border-none',
+            'bg-secondary-background hover:bg-secondary-background-hover',
+            'data-[state=open]:bg-secondary-background-hover'
+          )
+        "
+        :aria-label="t('linearMode.appModeToolbar.appBuilder')"
+      >
+        <i class="icon-[lucide--hammer] size-4" />
+        <span class="text-sm font-medium">
+          {{ t('linearMode.appModeToolbar.appBuilder') }}
+        </span>
+        <i class="icon-[lucide--chevron-down] size-4 text-muted-foreground" />
+      </button>
+    </template>
+    <template #default="{ close }">
+      <button
+        :class="
+          cn(
+            'flex w-full items-center gap-3 rounded-md bg-transparent px-3 py-2 text-sm border-none',
+            hasOutputs
+              ? 'cursor-pointer hover:bg-secondary-background-hover'
+              : 'opacity-50 pointer-events-none'
+          )
+        "
+        :disabled="!hasOutputs"
+        @click="onSave(close)"
+      >
+        <i class="icon-[lucide--save] size-4" />
+        {{ t('builderMenu.saveApp') }}
+      </button>
+      <div class="my-1 border-t border-border-default" />
+      <button
+        class="flex w-full cursor-pointer items-center gap-3 rounded-md bg-transparent px-3 py-2 text-sm border-none hover:bg-secondary-background-hover"
+        @click="onExitBuilder(close)"
+      >
+        <i class="icon-[lucide--square-pen] size-4" />
+        {{ t('builderMenu.exitAppBuilder') }}
+      </button>
+    </template>
+  </Popover>
+</template>
+
+<script setup lang="ts">
+import { storeToRefs } from 'pinia'
+import { useI18n } from 'vue-i18n'
+
+import Popover from '@/components/ui/Popover.vue'
+import { useAppModeStore } from '@/stores/appModeStore'
+import { cn } from '@/utils/tailwindUtil'
+
+import { useBuilderSave } from './useBuilderSave'
+
+const { t } = useI18n()
+const appModeStore = useAppModeStore()
+const { hasOutputs } = storeToRefs(appModeStore)
+const { setSaving } = useBuilderSave()
+
+function onSave(close: () => void) {
+  setSaving(true)
+  close()
+}
+
+function onExitBuilder(close: () => void) {
+  void appModeStore.exitBuilder()
+  close()
+}
+</script>