v0.20.7 restructure source and platform workspaces

setup.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PYTHON_BIN="${PYTHON_BIN:-python3}"
+
+usage() {
+  cat <<'EOF'
+Usage:
+  ./setup.sh init [platform|all]
+  ./setup.sh update [platform|all]
+
+Platforms:
+  antigravity
+  codex
+  opencode
+  claude-code
+  gemini-cli
+  all
+
+Commands:
+  init    Rebuild generated platform environments from src/ without pulling.
+  update  Run git pull --ff-only, then rebuild generated platform environments.
+EOF
+}
+
+cmd="${1:-}"
+platform="${2:-all}"
+
+case "$cmd" in
+  init)
+    "$PYTHON_BIN" "$ROOT_DIR/src/scripts/update_platform_envs.py" --platform "$platform" --skip-pull
+    ;;
+  update)
+    "$PYTHON_BIN" "$ROOT_DIR/src/scripts/update_platform_envs.py" --platform "$platform"
+    ;;
+  -h|--help|help|"")
+    usage
+    ;;
+  *)
+    echo "Unknown command: $cmd" >&2
+    usage >&2
+    exit 2
+    ;;
+esac