Add invalid cookie header tests for get_cookie_value #454
Description
Description
get_cookie_value in crates/common/src/cookies.rs does not explicitly test the invalid UTF-8 branch for the incoming Cookie header.
Done when
- Add a unit test for invalid UTF-8 cookie header bytes returning
None. - Keep existing valid cookie parsing behavior unchanged.
- Add any small guardrail assertions needed for missing/empty cookie inputs if they clarify behavior.
Affected area
- Core (synthetic IDs, cookies, GDPR)
Additional context
Source: test_gap.md, section Cookie Parsing Edge Cases.
Parent issue: #396