fix(cli): stop printing subprocess stdin in verbose output (#9350)

`--verbose` printed each subprocess command followed by everything piped
to its stdin, which can hold credentials. It now prints only the command
line, so `langgraph up --verbose`, `langgraph build` and `langgraph
deploy --verbose` no longer show the generated compose file or
Dockerfile (`langgraph dockerfile` still writes the Dockerfile out).

libs/cli/langgraph_cli/exec.py

@@ -44,11 +44,8 @@ async def subp_exec(
     on_stdout: Callable[[str], bool | None] | None = None,
 ) -> tuple[str | None, str | None]:
     if verbose:
-        cmd_str = f"+ {cmd} {' '.join(map(str, args))}"
-        if input:
-            print(cmd_str, " <\n", "\n".join(filter(None, input.splitlines())), sep="")
-        else:
-            print(cmd_str)
+        # Never echo stdin: it can carry secrets (docker login --password-stdin).
+        print(f"+ {cmd} {' '.join(map(str, args))}")
     if wait:
         await asyncio.sleep(wait)