[Docs] Missing Rust code examples in Accounts quickstart page

## Summary

The Accounts quickstart page (`docs/builder/quick-start/accounts.md`) provides Rust environment setup instructions but then only includes TypeScript code examples, leaving Rust developers with a dead end.

## Problem

The page instructs Rust users to set up their environment:

```bash
touch src/bin/demo.rs
cargo run --bin demo --release
```

It then presents tabbed code examples (TypeScript/Rust) for "Creating Accounts Programmatically" and "Creating a Token Faucet." However, the Rust tab appears to be empty or missing actual code, while the TypeScript tab has complete working examples.

A developer following the Rust path would:
1. Set up their Rust binary as instructed
2. Click the "Rust" tab for the code example
3. Find no code to put in the file they just created

## Suggested Fix

Add complete Rust code examples for the "Creating Accounts Programmatically" and "Creating a Token Faucet" sections, matching the pattern already used in the Notes & Transactions page (`notes.md`) which does include full Rust examples using `AccountBuilder`, `ClientBuilder`, etc.

The Rust examples in `notes.md` (mint.rs, consume.rs, send.rs) already demonstrate the same account creation flow and could serve as a reference for the missing code.

docs/builder/quick-start/notes.md（mint.rs、consume.rs、send.rs）にある既存のRustの例を調べて、AccountBuilderとClientBuilderを使用するパターンを理解します。次に、accounts.mdファイルを更新して、「Creating Accounts Programmatically」と「Creating a Token Faucet」のセクションに不足しているRustのコードスニペットを追加し、それらがTypeScriptの例と構造および機能が一致するようにします。変更をローカルでドキュメントをビルドして確認します。

索引モデルが issue の本文から書いたものです。