COMP: Run kw commit-msg hooks via pre-commit-managed Python

[hjmjohnson]

The kw-commit-msg and kw-prose-budget hooks ran via Utilities/Hooks/run-pixi-python.sh, which hardcoded the CWD-relative path ./.pixi/envs/pre-commit/bin/python. That pixi environment is per-worktree and only exists where pixi install -e pre-commit has run, so the hooks fail in fresh git worktrees built with a different pixi environment. This moves the two hooks onto pre-commit's own managed-environment mechanism (language: python) — the same one already used by gersemi/clang-format/black — and removes the launcher.

Why this is the right mechanism

• pre-commit's managed envs live in the shared ~/.cache/pre-commit (keyed to the repo, reused across all worktrees), not in per-worktree .pixi/envs/.
• Both kw-commit-msg.py and kw-prose-budget.py import only the standard library (os, re, subprocess, sys, pathlib), so no additional_dependencies are needed.
• The launcher (run-pixi-python.sh, added 2025-06-26) post-dated pre-commit adoption (2024-12-04); it reached for the pixi env instead of pre-commit's own env management.

Local verification

Reproduced the original failure in a fresh worktree, then with the pixi pre-commit env deleted confirmed pre-commit builds its own venv and both hooks pass:

[INFO] Installing environment for local.
kw commit-msg............................................................Passed
kw prose-budget (advisory)...............................................Passed

pre-commit run --all-files is green (gersemi, clang-format, black, all checks).

[greptile-apps]

Greptile Summary

This PR moves two commit-message hooks onto pre-commit-managed Python. The main changes are:

• kw-commit-msg now runs with language: python.
• kw-prose-budget now runs with language: python.
• The pixi-specific Python launcher was removed.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
.pre-commit-config.yaml	Updates the two commit-message hook entries to use pre-commit-managed Python while keeping the same script invocation shape.
Utilities/Hooks/run-pixi-python.sh	Removes the pixi-specific launcher after the changed hook entries no longer reference it.

_{Reviews (1): Last reviewed commit: "COMP: Run kw commit-msg hooks via pre-co..." | Re-trigger Greptile}