Add shellcheck hook and configuration

.claude/hooks/shellcheck.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+set -E -o errexit -o nounset -o pipefail
+
+# Exit silently if required tools are missing
+command -v shellcheck > /dev/null 2>&1 || exit 0
+command -v file > /dev/null 2>&1 || exit 0
+command -v jq > /dev/null 2>&1 || exit 0
+
+input=$(cat)
+file_path=$(printf '%s' "$input" | jq -r '.tool_input.file_path // empty')
+
+[[ -z "$file_path" || ! -f "$file_path" ]] && exit 0
+
+file_type=$(file --brief "$file_path")
+case "$file_type" in
+  *"Bourne-Again shell"*|*"bash"*|*"/bin/bash"*) ;;
+  *"shell script"*|*"/bin/sh"*) ;;
+  *) exit 0 ;;
+esac
+
+shellcheck --format=gcc "$file_path" >&2

.claude/settings.json

@@ -0,0 +1,15 @@
+{
+  "hooks": {
+    "PostToolUse": [
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": ".claude/hooks/shellcheck.sh"
+          }
+        ]
+      }
+    ]
+  }
+}