Pre-existing latent bug surfaced by the new @v2-gate scenario in
greet.feature (added in PR #56 follow-up): shouldEnableV2 used
strings.Contains(tags, "@v2") which matched the negation tag `~@v2`
as a positive inclusion. Result: the greet "v1" sub-test, intended
to run with v2_enabled=false, was actually starting the test server
with v2_enabled=true. The @v2-gate scenario asserting "v2 disabled →
404" got 200 instead.
Fix: parse the GODOG_TAGS expression by splitting on `&&` / `||` /
whitespace, then check each clause for exact `@v2` match (positive
inclusion only). The negation `~@v2` no longer matches.
The new BDD scenario is the regression test — without the fix, it
fails with status 200 instead of 404. With the fix, both greet "v1"
(v2 disabled) and "v2" (v2 enabled) sub-tests pass cleanly.
Verifier verdict: APPROVE. Race-clean. Full BDD suite green.
