Implementing pre-commit and pre-push git hooks

[seroperson]

Summary

Introduces a pre-commit / pre-push hooks for local checks and wires it into CI alongside a new pytest workflow.

Changes

• .pre-commit-config.yaml adds pre-commit checks trailing-whitespace, end-of-file-fixer, check-yaml, check-json, mixed-line-ending, check-added-large-files (500KB), ruff check --fix and ruff format; pre-push runs pytest tests/ -x -q.
• pyproject.toml: adds pre-commit to the dev dependency group; drops dead [tool.black] / [tool.isort] config.
• CONTRIBUTING.md: updated to uv-based workflow and documents the hooks.
• .github/workflows/lint.yml: now runs the full pre-commit suite (pre-commit stage). Same-repo PRs get auto-fix + auto-commit + verify; fork PRs get a single failing run.
• .github/workflows/test.yml: new workflow running uv run pytest tests/ -q on PRs to main/test. Previously tests were not running on CI, probably that's the reason why they were failing in tests/test_axon_handlers.py.

Installing hooks requires a manual command after uv sync: uv run pre-commit install --install-hooks.

The same PR for gittensor: entrius/gittensor#512

[anderdc]

delete data/pending_requests.json, randomly got in but should be gitignored