tools: add sgclaw browser runtime entry wrapper

tools/browser_runtime/sgclaw_browser_entry.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+CRATE_DIR="$(cd -- "${SCRIPT_DIR}/../.." && pwd)"
+BIN_PATH="${CRATE_DIR}/target/debug/sgclaw"
+MANIFEST_PATH="${CRATE_DIR}/Cargo.toml"
+
+needs_build=0
+if [[ ! -x "${BIN_PATH}" ]]; then
+  needs_build=1
+elif [[ "${MANIFEST_PATH}" -nt "${BIN_PATH}" ]]; then
+  needs_build=1
+elif [[ "${CRATE_DIR}/Cargo.lock" -nt "${BIN_PATH}" ]]; then
+  needs_build=1
+elif find \
+  "${CRATE_DIR}/src" \
+  "${CRATE_DIR}/third_party/zeroclaw/src" \
+  "${CRATE_DIR}/../skill_lib" \
+  -type f -newer "${BIN_PATH}" -print -quit | grep -q .; then
+  needs_build=1
+fi
+
+if [[ "${needs_build}" -eq 1 ]]; then
+  cargo build --manifest-path "${MANIFEST_PATH}" --bin sgclaw
+fi
+
+exec "${BIN_PATH}" "$@"