e2e: port batch subcommand to all five client CLIs

scripts/run-client-e2e-tests.ps1 expects each language CLI to expose a
`batch` subcommand that reads command lines from stdin, runs each
through the normal subcommand dispatch, writes the JSON result, then
a sentinel line `__MXGW_BATCH_EOR__`. The implementation lived on a
divergent branch (commit 6126099) that was never merged into main —
this commit ports the same protocol to HEAD's renamed CLIs so the
existing matrix script runs end-to-end.

The protocol:
  - one line of stdin = one full CLI invocation
  - successful output → stdout, then __MXGW_BATCH_EOR__
  - failure → {"error":"...","type":"error"} JSON on stdout, then
    __MXGW_BATCH_EOR__ (errors do NOT exit the loop)
  - empty line or EOF terminates the loop

Per-CLI additions:

  .NET: RunBatchAsync + per-line StringWriter capture, JSON error
    envelope when forceJsonErrors is true. Two new tests in
    MxGatewayClientCliTests covering the success and error paths.

  Go:   runBatch with bufio.Scanner, runs each line through the
    existing runWithIO switch with a buffered stdout writer. One new
    test pinning the EOR sentinel.

  Rust: new `Batch` variant on the clap Command enum, run_batch
    re-parses each line via Cli::try_parse_from. Two new tests in the
    inline mod tests block.

  Python: new `batch` click command in commands.py that uses
    CliRunner to dispatch each line; synthesises {"error",..."type"}
    JSON from click error messages when the captured output isn't
    already JSON-shaped. Three new tests in test_cli.py.

  Java: BatchCommand inner @Command with BufferedReader stdin loop,
    fresh commandLine() per dispatch with captured stdout/stderr
    PrintWriters; non-zero exit codes and uncaught exceptions both
    surface as JSON-error blocks. Two new tests.

Also fixes scripts/run-client-e2e-tests.ps1 line 705: the Python
invocation was still passing the old module name `mxgateway_cli` to
`python -m`; the client SDK rename in 397d3c5 moved it to
`zb_mom_ww_mxgateway_cli`. Without the fix the Python leg fails
with "No module named mxgateway_cli" before reaching open-session.

Verification: full matrix at the redeployed gateway (localhost:5120,
running ZB.MOM.WW.MxGateway.Server.exe / ZB.MOM.WW.MxGateway.Worker.exe)
with -SkipBulk -SkipReadWriteBulk -SkipParity -SkipAuth (those phases
exercise bulk read/write CLI subcommands that also live on the
divergent branch — porting those is a follow-up). All five clients
report `closed=true, addedItems=120, eventCount=5` and overall
`success=true`. Per-language unit tests pass:
  - dotnet: 59/59
  - go:     all packages clean
  - rust:   cargo test --workspace clean
  - python: 42/42
  - java:   gradle build SUCCESSFUL

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

clients/dotnet/ZB.MOM.WW.MxGateway.Client.Tests/MxGatewayClientCliTests.cs

@@ -368,6 +368,66 @@ public sealed class MxGatewayClientCliTests
         Assert.Contains("\"objectCount\": 99", text);
     }
 
+    /// <summary>Verifies that batch mode dispatches a single version command and emits the EOR sentinel.</summary>
+    [Fact]
+    public async Task RunAsync_Batch_DispatchesVersionAndWritesEndOfRecord()
+    {
+        using var output = new StringWriter();
+        using var error = new StringWriter();
+        using var input = new StringReader("version --json\n");
+
+        int exitCode = await MxGatewayClientCli.RunAsync(
+            ["batch"],
+            output,
+            error,
+            clientFactory: null,
+            standardInput: input);
+
+        Assert.Equal(0, exitCode);
+        string text = output.ToString();
+        Assert.Contains("\"gatewayProtocolVersion\":3", text);
+        Assert.Contains("__MXGW_BATCH_EOR__", text);
+        // The EOR marker must come after the JSON output.
+        int jsonIndex = text.IndexOf("\"gatewayProtocolVersion\"", StringComparison.Ordinal);
+        int eorIndex = text.IndexOf("__MXGW_BATCH_EOR__", StringComparison.Ordinal);
+        Assert.True(jsonIndex >= 0 && eorIndex > jsonIndex);
+        Assert.Equal(string.Empty, error.ToString());
+    }
+
+    /// <summary>Verifies that batch mode routes per-command errors to stdout as JSON between EOR markers.</summary>
+    [Fact]
+    public async Task RunAsync_Batch_WritesErrorsToStdoutAsJson()
+    {
+        using var output = new StringWriter();
+        using var error = new StringWriter();
+        // Unknown command should produce an error on the captured error stream,
+        // which batch mode re-emits to stdout inside the same delimited block.
+        using var input = new StringReader("nope-not-a-command\nversion\n");
+
+        int exitCode = await MxGatewayClientCli.RunAsync(
+            ["batch"],
+            output,
+            error,
+            clientFactory: null,
+            standardInput: input);
+
+        Assert.Equal(0, exitCode);
+        string text = output.ToString();
+        // Two records → two EOR markers.
+        int firstEor = text.IndexOf("__MXGW_BATCH_EOR__", StringComparison.Ordinal);
+        int secondEor = text.IndexOf(
+            "__MXGW_BATCH_EOR__",
+            firstEor + 1,
+            StringComparison.Ordinal);
+        Assert.True(firstEor > 0);
+        Assert.True(secondEor > firstEor);
+        // The unknown-command error message must be on stdout (not on stderr).
+        Assert.Contains("nope-not-a-command", text);
+        Assert.DoesNotContain("nope-not-a-command", error.ToString());
+        // The follow-up `version` line should still succeed.
+        Assert.Contains("gateway-protocol=", text);
+    }
+
     /// <summary>Fake CLI client for testing.</summary>
     private sealed class FakeCliClient : IMxGatewayCliClient
     {