test(repos): pin DELETE-idempotency contract for virtual member removal (#95)

[brandonrc]

Summary

Adds a single test case asserting that re-issuing DELETE /api/v1/repositories/:key/members/:member_key against a member that was already removed by a prior call returns 404, not 200/204.

The handler (update_virtual_member / remove_virtual_member in backend/src/api/handlers/repositories.rs) resolves member_key via service.get_by_key before attempting the delete, so the second call surfaces AppError::NotFound -> HTTP 404. A regression that swallowed the missing-row error and returned 200/204 would silently change the contract for clients (CLI, web, SDKs) that re-drive deletes on retry.

Fixes #95.

Why gated to v1.2.0

The endpoints exist in 1.1.x, but per the in-flight v1.1.9 release process we want this strict-contract test class to only run against the v1.2.0+ release-gate. New require_feature flag added to tests/lib/common.sh:

"virtual_member_strict_contract") echo "1.2.0" ;;

The flag is shared with the sibling follow-ups in #92, #93, #94 (each has its own PR). On 1.1.9 backends the case is recorded as a per-test JUnit <skipped/> (not a suite-level skip, so #870/#871/#888 silent-success protection is preserved).

Files

• tests/lib/common.sh -- adds virtual_member_strict_contract -> 1.2.0 to _feature_min_version.
• tests/repos/test-virtual-repo-member-remove.sh -- adds the new case immediately after the existing 404-on-unknown-member assertion. Reuses LOCAL_A, which was already removed earlier in the suite.

Validation

• bash -n tests/lib/common.sh and bash -n tests/repos/test-virtual-repo-member-remove.sh pass.
• The new case is wrapped in if require_feature ...; then ... fi, so on a 1.1.9 backend the case skips cleanly while the rest of the suite continues.

Test Plan

• Do not merge until v1.1.9 has shipped.
• Once merged, confirm the new case runs (not skipped) against a v1.2.0+ test deployment.
• Confirm the case is recorded as skipped (not failed) when run against the current release/1.1.x test target.