Add pre-commit for automated pre-push checks (#4660)

## Description / motivation

Versioned hook configuration and a single documented install path reduce
friction and drift between machines compared to copy-pasted shell hooks.

## How to test

1. `$ uv sync --group dev`
2. `$ uv run pre-commit install --hook-type pre-push`
3. Make any change, commit it, and push it

<img width="908" height="253" alt="image"
src="https://github.com/user-attachments/assets/d492e2a8-9f33-4adf-866e-04c54cbf57d9"
/>

### Details

- Add `.pre-commit-config.yaml` with a **pre-push** hook that runs
`./ninja check`
- Add `pre-commit` to the `dev` dependency group and refresh `uv.lock`.
- Update `docs/contributing.md`: contributors install hooks via `uv run
pre-commit` / `python -m pre_commit`, and drop the old suggestion of
manual `.git/hooks` scripts.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - -

Author: fernandolins

.pre-commit-config.yaml

@@ -0,0 +1,12 @@
+default_install_hook_types: [pre-push]
+
+repos:
+    - repo: local
+      hooks:
+          - id: ninja-check
+            name: ninja check
+            entry: bash -c 'if [ "$OS" = "Windows_NT" ]; then ./tools/ninja.bat check; else ./ninja check; fi'
+            language: system
+            pass_filenames: false
+            always_run: true
+            stages: [pre-push]

docs/contributing.md

@@ -102,17 +102,30 @@ For information on adding new translatable strings to Anki, please see
 ## Tests Must Pass
 
 Please make sure 'ninja check' completes successfully before submitting code.
-You can do this automatically by adding the following into
-.git/hooks/pre-commit or .git/hooks/pre-push and making it executable.
 
-```sh
-#!/bin/bash
-./ninja check
+[pre-commit](https://pre-commit.com/) is used to run that check from a Git hook.
+It is configured in `.pre-commit-config.yaml` at the repository root. After
+installing the dev dependencies (for example `uv sync --group dev`), run one of:
+
+```
+uv run pre-commit install --hook-type pre-push
+```
+
 ```
+python3 -m pre_commit install --hook-type pre-push
+```
+
+(`pre-commit` alone only works if that executable is on your `PATH`, for example
+after `pip install --user pre-commit` or with your virtual environment activated.)
+
+The bundled hook runs `./ninja check` on **pre-push** (not on every commit),
+because the full check suite can take a long time. You can still run
+`./ninja check` manually at any time.
 
-You may want to explicitly set PATH to your normal shell PATH in that script,
-as pre-commit does not use a login shell, and if your path differs Bazel will
-end up recompiling things unnecessarily.
+You may need to ensure your usual shell `PATH` is visible to the hook (for
+example if tools such as `ninja` are installed outside standard locations),
+because pre-commit does not use a login shell and a different path can cause
+extra rebuilds.
 
 If your change is non-trivial and not covered by the existing unit tests, please
 consider adding a unit test at the same time.

pyproject.toml

@@ -7,6 +7,7 @@ classifiers = ["Private :: Do Not Upload"]
 
 [dependency-groups]
 dev = [
+  "pre-commit",
   "mypy",
   "mypy-protobuf",
   "ruff",

tools/minilints/src/main.rs

@@ -36,6 +36,7 @@ const IGNORED_FOLDERS: &[&str] = &[
     ".mypy_cache",
     "./extra",
     "./ts/.svelte-kit",
+    "./.venv",
 ];
 
 fn main() -> Result<()> {