chore(ai-workflow): tighten agent workflow and worktree tooling (#1107)

* chore(ai-workflow): tighten agent workflow and worktree tooling

* fix(ai-workflow): address review feedback

* fix(ai-workflow): make format hook portable

scripts/agent-hooks/yarn-install.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+# afterFileEdit hook: Run yarn install when package.json is changed
+# Receives JSON via stdin: {"file_path": "...", "edits": [...]}
+
+input=$(cat)
+file_path=$(echo "$input" | grep -o '"file_path"[[:space:]]*:[[:space:]]*"[^"]*"' | sed 's/.*:.*"\([^"]*\)"/\1/')
+
+if [ -z "$file_path" ]; then
+  exit 0
+fi
+
+if [ "$file_path" = "package.json" ]; then
+  repo_root="$(git rev-parse --show-toplevel 2>/dev/null || pwd)"
+  cd "$repo_root" || exit 0
+  echo "package.json changed - running yarn install to update yarn.lock..."
+  yarn install
+fi
+
+exit 0