增加单独使用 Pilota 进行 Thrift Protobuf 编解码的示例与文档

## Feature Request

### Crates

### Motivation
需要在https://github.com/cloudwego/cloudwego.github.io/tree/main/content/zh/docs/pilota/guide 下增加文档，以及在examples 目录下增加示例

### Proposal

### Alternatives

Review the Pilota guide under cloudwego.github.io/content/zh/docs/pilota/guide and the repository's examples directory to understand the standalone Thrift and Protobuf encoding workflow. Add the requested documentation and examples, with completion shown by clear usage guidance and runnable standalone examples.

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