Add vulture dead-code scanner to pre-push validation

[Helios531]

Summary

The repository has recurring one-off dead-code cleanup issues, but no automated guard that prevents unused Python helpers, stale test fixtures, and framework leftovers from accumulating again.

Add vulture as a developer/CI pre-push check and clean up the dead code it currently reports.

Evidence

While analyzing the vulture-integration compare branch, the branch removed confirmed unused code such as:

• Dead helper methods and fields in gittensor/classes.py.
• Unused timestamp/repository helpers.
• Stale validator test fixtures that no tests reference.
• Unused test sentinel variables and callback argument names.

The branch also demonstrated that vulture can run cleanly when configured with repo-specific excludes for schema-like or framework-driven surfaces.

Expected behavior

• uv run vulture should pass locally after uv sync --extra dev.
• Pre-push validation should include vulture alongside pyright.
• CI pre-push checks should run vulture so future dead code is caught before merge.
• Known false positives should be handled in pyproject.toml via tool.vulture configuration, not by noisy inline suppressions.

Acceptance criteria

• Add vulture to dev dependencies.
• Add a pre-push vulture hook to .pre-commit-config.yaml.
• Add [tool.vulture] config with project paths, excludes, and ignored framework names.
• Remove currently reported dead code when safe.
• Keep runtime behavior unchanged.
• Validate with:

uv sync --extra dev
uv run vulture
uv run ruff check .
uv run ruff format --check .
uv run pyright
uv run pytest -q
SKIP=pytest uv run pre-commit run --all-files --hook-stage pre-push

[anderdc]

Closing — see #1251 for the provenance evidence. This issue was filed 3 minutes before #1251 and its body explicitly admits sourcing from the vulture-integration compare branch (@seroperson's branch, now #1253). It exists to anchor a Closes #N reference for the copied PR, not to surface an independently-discovered concern. The underlying tooling work is tracked in #1253.

Closing.