feat(client-http): Add compression support

[lambdalisue]

Summary

Add compression support to the HTTP client for both request and response handling.

Background

Currently, compression is handled entirely by fetch/browser automatically. This limits:

• Explicit control over Accept-Encoding header
• Ability to test compressed response handling
• Potential for request body compression

Proposed API

interface HttpClientConfig {
  // ...existing options
  
  /**
   * Compression configuration.
   */
  readonly compression?: {
    /**
     * Accept-Encoding values to send.
     * @default ["gzip", "deflate", "br"]
     */
    readonly acceptEncoding?: string[];
    
    /**
     * Whether to automatically decompress responses.
     * @default true
     */
    readonly decompress?: boolean;
  };
}

Test Coverage

Once implemented, integration tests can use echo-http service endpoints:

• GET /gzip - Return gzip-compressed response
• GET /deflate - Return deflate-compressed response
• GET /brotli - Return brotli-compressed response

Labels

enhancement, client-http

[lambdalisue]

Investigation Result

Deno's fetch automatically handles compression:

• Automatically sets Accept-Encoding: gzip, deflate, br
• Automatically decompresses responses and removes Content-Encoding header

Currently, there's no API to control this behavior in Deno. See denoland/deno#12291 for the feature request.

Options Considered

1. Accept-Encoding header override: Even if set manually, Deno may override or merge with automatic values
2. decompress control: Not currently possible with Deno's fetch

Recommendation

Keep this issue open and revisit when Deno adds support for controlling compression behavior (likely via Deno.createHttpClient options).