feat: add pinia stores (#170)

src/modules/pinia.ts

@@ -0,0 +1,15 @@
+import { createPinia } from 'pinia'
+import { UserModule } from '~/types'
+
+export const install: UserModule = ({ isClient, initialState, app }) => {
+  const pinia = createPinia()
+  app.use(pinia)
+  // Refer to
+  // https://github.com/antfu/vite-ssg/blob/main/README.md#state-serialization
+  // for other serialization strategies.
+  if (isClient)
+    pinia.state.value = (initialState.pinia) || {}
+
+  else
+    initialState.pinia = pinia.state.value
+}