Remove redundant dependencies and enforce exact pinning

[pahuchi-joe]

Summary

pyproject.toml carries dependencies that nothing imports and pins them inconsistently, so a fresh uv sync can quietly resolve to a different version graph than what uv.lock records.

Concrete redundancies found in the current file:

• Direct deps with zero call sites: bittensor-cli, bittensor-commit-reveal, levenshtein, python-dotenv
• Direct deps that are already transitives of bittensor: bittensor-wallet, plus fastapi and uvicorn in [debug] (their explicit pins were downgrading what bittensor's resolver wanted)
• pytz, whose only consumer is CHICAGO_TZ + parse_github_timestamp_to_cst in gittensor/validator/utils/datetime_utils.py, both unreferenced anywhere in gittensor/, neurons/, tests/, or scripts/ (already noted in chore: integrate pre-push vulture dead-code scanner #1253)

Pinning is also inconsistent: click, rich, substrate-interface, and pyright are unpinned, while everything else is exact-pinned.

Motivation

CONTRIBUTING.md:129 says "Avoid adding unnecessary dependencies". This brings pyproject.toml in line with that rule, retroactively. The exact-pinning makes installs reproducible across every contributor machine, every CI runner, and every validator in the network.