feat(python-runtime): package the Windows x64 dsh executable

Add node24-win-x64 as the only supported Windows runtime target and publish it as a py3-none-win_amd64 wheel containing the conventional dsh and ripgrep .exe payload names. Keep Windows ARM64 rejected explicitly so Python cannot claim a carrier that CI and release automation do not build.

Teach the pkg builder to require a native x64 Windows host, validate both node-pty ConPTY addons, copy @vscode's win32 ripgrep executable, and recognize pkg's .exe output. Extend runtime resolution, wheel staging, payload validation, and the preset closure check so the Windows-specific PowerShell plugins and sidecars fail loud when omitted.

The sidecar resolver now maps a packaged main.exe to main-rg.exe; focused TypeScript and Python tests cover that name, the win_amd64 manifest, x64-only host selection, complete wheel payload, ConPTY inventory, and platform-conditioned plugin closure.

python/sdk/src/deepseek_harness/client.py

@@ -93,11 +93,14 @@ class HarnessClient:
         self._start_stderr_thread()
 
     def close(self) -> None:
+        """Close the runtime after a bounded opportunity to flush durable state."""
         proc = self._proc
         if proc is None:
             return
+        shutdown_completed = False
         try:
             self.request("shutdown", None, response_model=_ShutdownResponse, timeout_seconds=self.config.shutdown_timeout_seconds)
+            shutdown_completed = True
         except Exception as exc:
             self._stderr_lines.append(f"shutdown request failed: {exc}")
         if proc.stdin:
@@ -105,16 +108,22 @@ class HarnessClient:
                 proc.stdin.close()
             except Exception as exc:
                 self._stderr_lines.append(f"stdin close failed: {exc}")
+        if shutdown_completed:
+            try:
+                proc.wait(timeout=self.config.shutdown_timeout_seconds)
+            except subprocess.TimeoutExpired:
+                pass
         if proc.poll() is None:
             try:
                 proc.terminate()
             except ProcessLookupError:
                 pass
-        try:
-            proc.wait(timeout=self.config.shutdown_timeout_seconds)
-        except subprocess.TimeoutExpired:
-            proc.kill()
-            proc.wait()
+        if proc.poll() is None:
+            try:
+                proc.wait(timeout=self.config.shutdown_timeout_seconds)
+            except subprocess.TimeoutExpired:
+                proc.kill()
+                proc.wait()
         self._proc = None
         self._fail_waiters(self._runtime_closed_error("DeepSeek Harness runtime closed"))
         if self._reader_thread and self._reader_thread.is_alive():