feat(hooks): normalize commit subjects

[marcus]

Summary

• add a local commit-msg hook that normalizes conventional commit subjects while preserving bodies and trailers
• install both hooks through make install-hooks using worktree-safe wrappers built from git rev-parse --git-path hooks
• update repo-authored commit message examples and release automation to match the normalized format

Verification

• bash -n scripts/commit-msg.sh scripts/pre-commit.sh
• isolated temp repo + linked worktree: make install-hooks plus valid/normalized/malformed/body+trailers/release subject cases
• go test ./test/e2e -count=1
• go test ./...

Notes

• go test ./... initially hit a flaky TestChaosSync failure in test/e2e; rerunning the package once passed, and the subsequent full suite passed from cache.