build: point lint tasks at pre-commit

[davidberenstein1957]

Fixes the task lint / task format tasks so they run what CI actually enforces.

What changed

-precommit = "c"
-lint = "black --check --diff . && ruff check . && mypy ."
-format = "black . && ruff check --fix --exit-non-zero-on-fix ."
+precommit = "pre-commit run --all-files"
+format = "pre-commit run --all-files"

Also drops the now-unreferenced ruff dev dependency, and removes the docs-check-drift task, which pointed at scripts/check-docs-drift.py — a file that does not exist.

Why

There is no ruff config anywhere in the repo, ruff is not in .pre-commit-config.yaml, and .github/workflows/pre-commit.yml is the only lint job in CI. So ruff check . was running against its own defaults, unrelated to the style the codebase is written in and never gating anything. mypy . likewise walked carbonserver/ and webapp/ rather than the -m codecarbon scope the existing mypy-check task uses.

The practical effect was that anyone following CLAUDE.md's instruction to run these before submitting got ~1300 findings and ~120 rewritten files on an otherwise clean tree — and ruff's SIM117 autofix rewrote a nested with in tests/test_powermetrics.py into syntactically invalid Python.

Verification

$ uv run task format
autoflake................................................................Passed
isort....................................................................Passed
black....................................................................Passed
flake8...................................................................Passed

Passes clean on origin/master, matching uv run pre-commit run --all-files.

Notes for review

• The lint task is gone, not aliased. pre-commit checks and fixes in one pass, so a lint task pointing at it would rewrite the working tree — the opposite of what someone typing lint expects. There is one task, format, and docs/how-to/agent-instructions.md (a.k.a. CLAUDE.md) now points at it.
• Dropping mypy from the lint path is deliberate. mypy . walked carbonserver/ and webapp/ instead of the package, it is not in .pre-commit-config.yaml and not in CI, so it gated nothing while producing noise. mypy-check, scoped to -m codecarbon, is untouched and still available for anyone who wants a type check.
• Removing ruff from the dev group is deliberate: leaving an unconfigured, unenforced linter installed is what caused this. If the project wants ruff, it should land as a configured pre-commit hook with the codebase brought into line in its own PR.

Closes #1368

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.43%. Comparing base (065d0e6) to head (5f12ba9).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1369      +/-   ##
==========================================
+ Coverage   91.39%   91.43%   +0.03%     
==========================================
  Files          49       49              
  Lines        5056     5056              
==========================================
+ Hits         4621     4623       +2     
+ Misses        435      433       -2     

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