feat: add git hooks for pre-push validation and post-merge auto-deploy

- .githooks/pre-push: validate Pd patches via python3 pd-validator
- .githooks/post-merge: auto-restart services when systemd/scripts change
- install.sh: configure core.hooksPath at install time
- justfile deploy: set hooksPath after git pull

.githooks/pre-push

@@ -0,0 +1,23 @@
+#!/bin/bash
+# pre-push: validate Pd patches before pushing
+set -euo pipefail
+
+REPO="$(cd "$(dirname "$0")/.." && pwd)"
+
+# Only check if there are any .pd files staged or changed
+STAGED_PD=$(git diff --cached --name-only -- '*.pd' 2>/dev/null || true)
+CHANGED_PD=$(git diff --name-only -- '*.pd' 2>/dev/null || true)
+
+if [ -z "$STAGED_PD" ] && [ -z "$CHANGED_PD" ]; then
+    exit 0
+fi
+
+echo "[githook:pre-push] Validating Pd patches..."
+cd "$REPO"
+if python3 pd-validator/validate.py pd/*.pd; then
+    echo "[githook:pre-push] All patches valid"
+    exit 0
+else
+    echo "[githook:pre-push] Patch validation FAILED — fix before pushing"
+    exit 1
+fi