fix(middleware): fix Accept-Encoding matching in compress middleware

[boatnoah]

Fixes #1069

Summary

matchAcceptEncoding used substring matching, so values like bgzip could match gzip, and encodings explicitly rejected with q=0 were still selected.

Fix

Parse each Accept-Encoding item as an encoding token plus parameters, compare the token and q parameter name case-insensitively, and reject matches with a parsed quality value of 0 or lower.

This intentionally keeps the existing server-side encoder precedence and does not add wildcard or q-priority negotiation.

Tests

Added helper-level regression coverage for exact matching, substring false positives, whitespace, mixed-case tokens and parameters, q=0 / q=0.0, and multiple accepted encodings.

Added middleware-level cases for gzip;q=0 returning no encoding and falling back to deflate when available.