fix(dev): tsx watch not detecting workspace package changes

tsx watch's symlink-based file watching doesn't trigger on changes to
pnpm workspace packages (tsx#221). Add --include flags for packages/core
and packages/node-runtime source directories to both dev:serve script
and vite.web.config.mts auto-serve plugin. Extract long command to
scripts/dev-serve.sh for cleaner package.json.

scripts/dev-serve.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# Dev server with tsx watch — monitors workspace packages for changes.
+set -e
+
+pnpm run ensure:server-native
+
+exec tsx watch \
+  --include 'packages/core/src/**' \
+  --include 'packages/node-runtime/src/**' \
+  packages/server/src/cli.ts serve "$@"