fix(interceptor): limit response error body size

[mcollina]

This relates to...

Hardening interceptors.responseError() against retaining arbitrarily large decoded error bodies.

Rationale

responseError automatically decodes JSON and plain-text error responses so they can be attached to ResponseError.body. Those bodies previously had no interceptor-specific retention limit.

Changes

Features

• Add a maxSize option to interceptors.responseError().
• Default the retained error body to 1 MiB; maxSize: 0 restores unlimited retention.
• Add ResponseError.bodyTruncated so callers can detect a retained prefix.

Bug Fixes

• Bound JSON and plain-text error body retention by decoded input bytes.
• Keep truncated JSON as a string rather than parsing an incomplete document.
• Preserve bounded behavior when responseError is composed after decompression.

Breaking Changes and Deprecations

Error bodies larger than 1 MiB are truncated by default. Applications that intentionally consume larger error bodies can configure a larger maxSize or set it to 0 to retain the previous unlimited behavior.

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

Validation

• npm run test:unit — 1,568 passed, 5 skipped
• npx borp -p "test/interceptors/response-error.js" — 14 passed
• npm run test:typescript
• npm run lint
• git diff --check

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.59459% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.10%. Comparing base (7bc9dd6) to head (afbf59d).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/interceptor/response-error.js	94.44%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5942      +/-   ##
==========================================
- Coverage   94.04%   86.10%   -7.95%     
==========================================
  Files         110      115       +5     
  Lines       40252    45620    +5368     
==========================================
+ Hits        37856    39282    +1426     
- Misses       2396     6338    +3942     

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[mcollina]

CI note: the four failing Node.js 22 jobs all abort in the unrelated test/http2-request-never-settles.js test with Node's Assertion failed: onread->IsFunction(). I reran the failed jobs and got the same result. The same Node.js 22 jobs are currently failing on unrelated PRs #5941 and #5943, while this PR's Node.js 24–26 matrix, lint, type tests, CodeQL, fuzzing, and benchmarks pass.