Select Ruby for tracked .rb files alongside existing language detection. Covers qctl Java/Ruby/Actions, Ruby-only repositories and untracked-file exclusion.
Validation: red/green regression, seven selector tests, actionlint and two workflow contracts passed; actual qctl branch inventories select the expected languages. Consumer repins and scanner setup changes are outside this PR.
Co-Authored-By: Codex (GPT-6) <noreply@openai.com>
