feat(gateway): generate shared TypeScript contracts

Define gateway payloads as Python TypedDict contracts and generate the shared
TypeScript surface through ts-type during shared, TUI, and desktop workflows.

scripts/generate_gateway_types.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+"""Generate TypeScript gateway contracts from ``tui_gateway.contracts``."""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+from tempfile import NamedTemporaryFile
+
+import ts_type as ts
+from tui_gateway.contracts import (
+    GatewayMcpServerStatus,
+    GatewayProjectInfo,
+    GatewaySessionRuntimeInfo,
+    GatewayUsage,
+)
+
+ROOT = Path(__file__).resolve().parents[1]
+OUTPUT = ROOT / "apps/shared/src/generated/gateway.ts"
+
+
+def main() -> None:
+    for contract in (
+        GatewayMcpServerStatus,
+        GatewayProjectInfo,
+        GatewayUsage,
+        GatewaySessionRuntimeInfo,
+    ):
+        ts.generator.add(contract, "gateway", contract.__name__)
+
+    source = ts.generator.render()["gateway"]
+    output = "// Generated by scripts/generate_gateway_types.py. Do not edit.\n\n" + source + "\n"
+    OUTPUT.parent.mkdir(parents=True, exist_ok=True)
+
+    # Workspace checks may run concurrently. Replacing an already-complete
+    # temporary file means a typecheck always observes either version, never a
+    # partially-written module.
+    with NamedTemporaryFile("w", encoding="utf-8", dir=OUTPUT.parent, delete=False) as file:
+        file.write(output)
+        temp_path = Path(file.name)
+    os.replace(temp_path, OUTPUT)
+
+
+if __name__ == "__main__":
+    main()