Close response inflater resources on every exit

[OskarEichler]

Summary

Close the response inflater in an ensure block after finishing and reading the inflated-byte count. This releases the zlib stream resources on success and failure instead of leaving cleanup to GC, while retaining existing response-length and exception behavior.

Reproduction

Keep references to the Zlib::Inflate objects created by Net::HTTPResponse::Inflater, then read a complete gzip response. Before this change, closed? remains false after the response finishes. It also remains false after an invalid compressed stream or a failing destination. Afterward, the streams are immediately closed in all these paths, even while references remain alive.

Zlib::ZStream#close provides explicit stream cleanup; calling finish alone does not close it.

Verification

• Ruby 4.0.6 through rbenv; existing bundle exec rake test: 201 tests / 914 assertions / zero failures or errors, baseline and isolated patch.
• 34 focused checks cover gzip/zlib, empty content, fixed-length/chunked/EOF framing, decoded body/length preservation and immediate closure. Failure cases cover invalid compressed data, a finish-time error through the internal inflater wrapper, and a raising destination, preserving the existing exception class.
• Syntax and git diff --check pass; supplemental Lint scan has the same 25 baseline findings.
• No test/spec files were added or modified, per this contribution's no-new-tests constraint; focused reproductions ran externally.

Compatibility and limitations

No public API/dependency/Ruby-requirement change. The internal wrapper gains close; finish and bytes_inflated retain their behavior and are called before close. No claim of measured production RSS improvement: verification observes explicit closure with retained references. This does not change existing truncated-response/error-suppression policies. Other Ruby/OS combinations and optional external OpenSSL checks were not run.