store-and-sync-state: use this.sql synchronously

[mmkal]

Summary

fixes #25018

copying summary from there:

Existing documentation URL(s)

https://developers.cloudflare.com/agents/api-reference/store-and-sync-state/#sql-api

The first example of the this.sql helper uses await which is functional but misleading that it's necessary(?) and doesn't showcase the value:

export class MyAgent extends Agent<Env> {
  async onRequest(request: Request) {
    let userId = new URL(request.url).searchParams.get('userId');

    // 'users' is just an example here: you can create arbitrary tables and define your own schemas
    // within each Agent's database using SQL (SQLite syntax).
    let user = await this.sql`SELECT * FROM users WHERE id = ${userId}`
    return Response.json(user)
  }
}

I think it's also probably misleading to imply the return value from that particular sql query is user given this.sql returns an array? Have I got this wrong?

What changes are you suggesting?

An sync/singular example like

let [user] = this.sql`select * from users where id = ${userId}`

Additional information

Intro blog mentions it's synchronous! https://blog.cloudflare.com/sqlite-in-durable-objects/#reads-and-writes-are-synchronous

Screenshots (optional)

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