feat: add install.sh for one-command hook activation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

install.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# install.sh — wire circuitforge-hooks into the calling git repo
+# Usage: bash /Library/Development/CircuitForge/circuitforge-hooks/install.sh
+# Usage (quiet): bash /Library/Development/CircuitForge/circuitforge-hooks/install.sh --quiet
+set -euo pipefail
+
+HOOKS_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/hooks" && pwd)"
+QUIET=false
+[[ "${1:-}" == "--quiet" ]] && QUIET=true
+
+if ! git rev-parse --git-dir &>/dev/null; then
+    echo "ERROR: not inside a git repo. Run from your product repo root."
+    exit 1
+fi
+
+git config core.hooksPath "$HOOKS_DIR"
+
+if [[ "$QUIET" == "false" ]]; then
+    echo "CircuitForge hooks installed."
+    echo "  core.hooksPath → $HOOKS_DIR"
+    echo ""
+    echo "Verify gitleaks is available: gitleaks version"
+fi