App mode - store - 1 (#9022)

## Summary

Adds a store to control the mode the app is in (app, graph, builder)
Changes the existing linearMode in canvasStore to update new store

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9022-App-mode-store-1-30d6d73d365081498df1c1192c9860f0)
by [Unito](https://www.unito.io)

src/stores/appModeStore.ts

@@ -0,0 +1,40 @@
+import { defineStore } from 'pinia'
+import { readonly, computed, ref } from 'vue'
+
+type AppMode = 'graph' | 'app' | 'builder:select' | 'builder:arrange'
+
+export const useAppModeStore = defineStore('appMode', () => {
+  const mode = ref<AppMode>('graph')
+  const builderSaving = ref(false)
+  const hasOutputs = ref(true)
+
+  const isBuilderMode = computed(
+    () => mode.value === 'builder:select' || mode.value === 'builder:arrange'
+  )
+  const isAppMode = computed(
+    () => mode.value === 'app' || mode.value === 'builder:arrange'
+  )
+  const isGraphMode = computed(
+    () => mode.value === 'graph' || mode.value === 'builder:select'
+  )
+  const isBuilderSaving = computed(
+    () => builderSaving.value && isBuilderMode.value
+  )
+
+  return {
+    mode: readonly(mode),
+    isBuilderMode,
+    isAppMode,
+    isGraphMode,
+    isBuilderSaving,
+    hasOutputs,
+    setBuilderSaving: (newBuilderSaving: boolean) => {
+      if (!isBuilderMode.value) return
+      builderSaving.value = newBuilderSaving
+    },
+    setMode: (newMode: AppMode) => {
+      if (newMode === mode.value) return
+      mode.value = newMode
+    }
+  }
+})