This patch fixes the Accept-Encoding quality calculation logic in the
HTTP transaction cache and updates test files to reflect the corrected
behavior, removing workarounds for previously broken cache matching.

Cache quality calculation improvements:
- Replace multiplicative quality combining with minimum quality
  selection for multiple content encodings
- Simplify wildcard matching to return quality directly
- Remove gzip-specific fallback logic that bypassed normal quality
  calculation and caused inconsistent cache behavior

Test updates for corrected behavior:
- Remove NOTICE comments describing broken cache matching behavior
- Update test expectations to match correct cache responses instead
  of workaround responses
- Fix cache hit/miss expectations for multi-encoding scenarios
- Add missing Content-Encoding headers in server responses
- Update response identifiers to match the actual cached alternates

Specific test corrections:
- "br, compress, gzip" now correctly matches "Br-Gzip-Accept-Encoding"
  instead of falling back to "Gzip-Accept-Encoding"
- "zstd, compress, gzip" now correctly matches "Zstd-Gzip-Accept-Encoding"
  instead of falling back to "Gzip-Accept-Encoding"
- "zstd, gzip;q=0.8" now correctly matches "Zstd-Gzip-Accept-Encoding"
  instead of falling back to "Gzip-Accept-Encoding"
- Individual encoding requests now create proper cache alternates
  instead of incorrectly matching empty encoding alternates

The previous multiplicative quality calculation (q_a * q_b) was causing
unexpectedly low quality scores and incorrect cache alternate selection.
The new minimum quality approach ensures that multi-encoding responses
are properly cached and matched according to HTTP content negotiation
standards.

All test cases now pass without workarounds and demonstrate correct
cache behavior for all compression algorithms (gzip, brotli, zstd)
across various Accept-Encoding

… for compression encoding

- Add support for configurable compression levels per host:
  * gzip-compression-level (1-9, default 6)
  * brotli-compression-level (0-11, default 6)
  * brotli-lgwin (10-24, default 16)
  * zstd-compression-level (1-22, default 12)

This enables fine-tuning compression performance vs. speed trade-offs
on a per-host basis