Test definition file missing .feature extension skips version rewrite and Validation #109

Problem description

code/Test_definitions/device-data-volume-subscriptions-retrieveDeviceDataVolumeSubscriptionList is missing its .feature extension. Introduced by #103, present on main.

Two consequences:

• The release-snapshot version rewrite skips it: it still says vwip (line 2) and {apiroot}/device-data-volume-subscriptions/vwip/subscriptions (line 18), where every other Test_definitions file in the same PR was rewritten to 0.2.0-rc.1 / v0.2rc1. Confirmed on the r2.1 rc snapshot (#108).
• CAMARA Validation's Gherkin linter globs *.feature and never opens this file, so the reported PASS (0 errors, 0 warnings, 0 hints) is not evidence this file is clean.

Expected behavior

Rename the file to end in .feature so it is picked up by both the version-rewrite step and CAMARA Validation.

Additional context

Raised as a CHANGES_REQUESTED review on #108 (2026-09-04); the fix has to land on main, so it requires a discard/re-create snapshot cycle for r2.1.