#345: Fix Content-Type application/zip on gzip-encoded upload bodies

[VasilevNStas]

Problem

BazaRb#zipped set Content-Type: application/zip on gzip-compressed upload bodies. The body is a gzip stream (written by Zlib::GzipWriter), not a ZIP archive. The Content-Encoding: gzip header already names the transport encoding. The wrong media type causes servers that route by Content-Type before decoding to reject legitimate uploads.

Solution

Removed 'Content-Type' => 'application/zip' from the zipped method. The original Content-Type: application/octet-stream set by upload now survives through compression. Only Content-Encoding: gzip and Content-Length are added when compression is on.

Verification

• bundle exec rubocop — 0 offenses
• All tests pass (46 edge tests, 132 assertions)
• Updated test_push_compressed_content to expect application/octet-stream
• New test test_push_compressed_headers_are_correct verifies both headers via WebMock

Closes #345.

[VasilevNStas]

@yegor256 please review

[VasilevNStas]

CI failure note: The test_live_full_cycle failure in the CI is unrelated to this PR. It's a pre-existing infrastructure issue with the Zerocracy platform (jobs not completing on the live server). See issue #354 for details and discussion.

All 118 other tests pass, and all non-live checks (rubocop, copyrights, markdown-lint, pdd, reuse, xcop, actionlint, typos, yamllint) pass successfully.

[0crat]

@VasilevNStas Thanks for the contribution! You've earned +20 points for this: +24 as a basis; -4 for too few (26) hits-of-code as per our policy which deducts 4 points when contributing less than 30 hits-of-code. Remember, our bonus system rewards consistent, quality contributions while encouraging optimal code size - aim for 30+ hits-of-code to avoid the deduction and maximize your bonus! Please, keep them coming. Your running score is +346; don't forget to check your Zerocracy account too.