Add shared pre-commit hook: ruff format + ruff check

Author: kks32

docs/installation.md

@@ -42,6 +42,15 @@ cd dapi
 pip install -e .
 ```
 
+### Set up pre-commit hook
+
+The repo includes a pre-commit hook that auto-formats with `ruff format` and blocks commits that fail `ruff check`:
+
+```bash
+cp scripts/pre-commit .git/hooks/pre-commit
+chmod +x .git/hooks/pre-commit
+```
+
 ## Update
 
 ```bash

scripts/pre-commit

@@ -0,0 +1,15 @@
+#!/bin/sh
+# Auto-format and lint with ruff before committing
+ruff format . 2>/dev/null || .venv/bin/ruff format .
+git add -u
+
+# Lint check — blocks commit on failure
+if ruff check . 2>/dev/null; then
+    exit 0
+elif .venv/bin/ruff check . 2>/dev/null; then
+    exit 0
+else
+    echo ""
+    echo "Commit blocked: ruff check found errors. Fix them and try again."
+    exit 1
+fi