Revise backpressure examples in streams documentation

先查看当前关于 streams 和 backpressure 的文档及其压缩示例，然后检查讨论和其中引用的 pull request 90 以了解背景。完成的标准是：文档对比 Node.js 的 buffering API 和 streaming API，包含 CommonJS 和 ESM 示例，解释忽略 backpressure 及其对内存的影响，并删除关于归档比较的注释。

Problem

The current backpressure documentation contains examples that may be confusing or technically inaccurate.

Specifically:

The compression example uses the zip command in a way that does not clearly demonstrate the role of Node.js stream backpressure.
It implies that using a command-line compression utility loads the entire file into memory, which is generally not true and depends on the implementation.
The example focuses on comparing archive outputs rather than illustrating the memory and throughput implications of buffering versus streaming.

See discussion: https://stackoverflow.com/questions/79821132/node-js-back-pressure-documentation-whats-the-relevance-of-their-example

Proposed Solution

Update the examples to use Node.js APIs directly:

Replace the current zip example with fs.readFileSync() + zlib.gzipSync() examples (CommonJS and ESM variants) to demonstrate a buffering approach.
Add a corresponding streaming example using Node.js streams and zlib.createGzip().
Include an explicit example showing a stream implementation that ignores backpressure and explain why it can lead to excessive memory consumption or out-of-memory conditions.
Remove the note about comparing the resulting archives, as it does not help explain backpressure behavior.

Motivation

The primary goal of the backpressure documentation should be to help readers understand how streams regulate data flow and memory usage. Using examples based entirely on Node.js APIs makes the comparison clearer

https://github.com/nodejs/learn/pull/90