Fix ApiContext header step matching (quoted regex + JSON shortcut)

[zakhar-huzenko]

Summary

Turnip placeholders (:headerName, :value) only match unquoted tokens built from [\w.,]+ (no -, no /). That breaks real headers such as Content-Type and MIME values such as application/json, which led consumers to work around the context with reflection.

Changes

• Request header steps now use explicit regex patterns that require double-quoted header names and values, so Content-Type and application/json match reliably.
• Multiline request header step uses the same quoted header name rule.
• Given the request JSON content type is used sets Content-Type: application/json so POST/PUT/PATCH JSON-encoding in iSendRequestToRoute is obvious without a separate hack context.
• Response header (Then / And) steps updated to the same quoted form for consistency.
• docs/steps.md: documents the quoting requirement, the JSON shortcut, JSON body encoding for write methods, and a short breaking-change note for unquoted header steps.
• Tests: ApiContextStepPatternTest asserts the regex matches quoted Content-Type / application/json and rejects the old unquoted form; unit test for the new JSON content-type step. Step-pattern test uses preg_match + default policy constructors so Behat 3.6 (composer --prefer-lowest) passes CI.

Verification

composer run dev-checks (composer validate, PHPStan max, PHPCS, PHPUnit) passes on this branch. PHPUnit also passes with composer update --prefer-lowest.

  

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.12%. Comparing base (0c06f56) to head (ecb08dc).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop      #59      +/-   ##
=============================================
+ Coverage      98.10%   98.12%   +0.01%     
- Complexity        75       76       +1     
=============================================
  Files              6        6              
  Lines            264      266       +2     
=============================================
+ Hits             259      261       +2     
  Misses             5        5              

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