chore: add pre-push git hook for commit validation

[agherzan]

Add githooks/pre-push that validates commits before pushing.
The hook compares against remote's HEAD for new branches or the
merge-base with the remote for existing branches (only checks
divergent commits).

Add 'task install-githooks' to install the hook locally.

[Copilot]

Pull request overview

Adds a local pre-push Git hook to run gitlance commit validation before pushing, plus a Taskfile task to install the hook.

Changes:

• Add githooks/pre-push hook script to validate commit ranges on push.
• Add task install-githooks to copy the hook into the local Git hooks directory.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
Taskfile.yml	Adds an install task to place the pre-push hook locally.
githooks/pre-push	Implements pre-push validation by running gitlance over the push range.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

[pedoch]

LGTM!

Only caveat I think I see is that you don't validate commits in new branches with not base remote (fresh repo for example). Also seems like it would be more useful as a precommit hook.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (2)

Taskfile.yml:30

• install-githooks assumes the resolved hooks directory already exists. In some setups (e.g., custom hooksPath, unusual worktree layouts), the directory may be missing and cp will fail. Create the directory before copying the hook.

      - cp githooks/pre-push "{{.HOOKS_DIR}}/"
      - chmod +x "{{.HOOKS_DIR}}/pre-push"
      - echo "✓ Git hooks installed to {{.HOOKS_DIR}}"

githooks/pre-push:47

• When no merge-base is found for a new branch, the script falls back to the repository root commit as base. gitlance excludes the base commit from its range, so the root commit itself won’t be validated in this fallback path. Prefer using the local remote-tracking HEAD as the base when available (it will be outside the new branch history for unrelated histories, and will still properly exclude already-shared history when related).

        # Fall back to root commit if no common ancestor found
        if [ -z "$base" ]; then
            base=$(git rev-list --max-parents=0 "$local_oid" | head -1)
        fi