Display scenario tags in gherkin terminal reporter

[ryux1]

Closes #476.

Scenario tags are already serialized into the report context, but the Gherkin terminal reporter never renders them. This adds a small shared writer and emits (tags: ...) after the scenario result in both verbose modes. Untagged scenario output remains unchanged.

Validation:

• pytest -q: 144 passed, 1 skipped
• focused reporter suite: 16 passed
• Ruff check and format on the changed Python files
• MyPy: clean across 18 source files

The repository-wide Ruff run still reports the pre-existing ISC004 finding in tests/generation/test_generate_missing.py:80; this PR does not touch that file.

[ryux1]

Closing as a duplicate. I missed the existing #807 and #477 because my initial search was limited to references to issue #476. Sorry for the noise; the existing contributors should retain ownership of this work.