feat: submitStreaming + detached-invocation client (T2/T3)

Regenerates the gRPC stubs from the updated proto and adds:
- HubClient.submitStreaming(...) -> Stream<SubmitStreamEvent>: follow a
  flow execution live (step markers, module emit-events, terminal
  result/error). Works over native gRPC and, on web, gRPC-Web (the
  same conditional channel factory the rest of the SDK uses).
- submit(..., detach: true) and getInvocationStatus /
  getInvocationResult / cancelInvocation wrappers (T3).
- SubmitStreamEvent + InvocationStatus re-exported as typedefs.

Shared _buildSubmitRequest between submit + submitStreaming. analyze
clean, tests pass.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/src/hub_client.dart

@@ -86,6 +86,11 @@ typedef StoreSearchResponse = pb.StoreSearchResponse;
 typedef InstallModuleResponse = pb.InstallModuleResponse;
 typedef Payload = pb_common.Payload;
 typedef SubmitResponse = pb.SubmitResponse;
+// Live-stream (T2) + detached-invocation (T3) wire types, re-exported
+// so consumers of [HubClient.submitStreaming] don't import the
+// generated package directly.
+typedef SubmitStreamEvent = pb.SubmitStreamEvent;
+typedef InvocationStatus = pb.InvocationStatus;
 
 /// Typed client for the F∆I Hub gRPC surface. Construct once,
 /// reuse for the process lifetime, call [close] on shutdown.
@@ -779,8 +784,80 @@ class HubClient {
     Map<String, Uint8List> fileInputs = const {},
     Map<String, Object?> jsonInputs = const {},
     Map<String, String> fileMimeTypes = const {},
+    bool detach = false,
   }) async {
-    final req = pb.SubmitRequest()..flowYaml = utf8.encode(flowYaml);
+    return _hub.submit(_buildSubmitRequest(
+      flowYaml: flowYaml,
+      textInputs: textInputs,
+      fileInputs: fileInputs,
+      jsonInputs: jsonInputs,
+      fileMimeTypes: fileMimeTypes,
+      detach: detach,
+    ));
+  }
+
+  /// Submit a flow and follow its execution live (server streaming).
+  ///
+  /// Yields [pb.SubmitStreamEvent]s in order: `stepStarted` /
+  /// `stepFinished` markers, `moduleEvent`s (a module's ephemeral
+  /// `host.emit-event`s), and finally either `finalResult` (== the
+  /// unary [submit] response) or `error`. Works over native gRPC and,
+  /// on web targets, gRPC-Web. Same inputs as [submit].
+  ///
+  /// ```dart
+  /// await for (final ev in hub.submitStreaming(flowYaml: yaml)) {
+  ///   if (ev.hasModuleEvent()) print('${ev.moduleEvent.name}');
+  ///   if (ev.hasFinalResult()) print(ev.finalResult.outputs);
+  /// }
+  /// ```
+  Stream<SubmitStreamEvent> submitStreaming({
+    required String flowYaml,
+    Map<String, String> textInputs = const {},
+    Map<String, Uint8List> fileInputs = const {},
+    Map<String, Object?> jsonInputs = const {},
+    Map<String, String> fileMimeTypes = const {},
+  }) {
+    return _hub.submitStream(_buildSubmitRequest(
+      flowYaml: flowYaml,
+      textInputs: textInputs,
+      fileInputs: fileInputs,
+      jsonInputs: jsonInputs,
+      fileMimeTypes: fileMimeTypes,
+    ));
+  }
+
+  /// Status of a detached invocation (T3). Throws a [GrpcError] with
+  /// code `notFound` for an unknown id.
+  Future<InvocationStatus> getInvocationStatus(String invocationId) {
+    return _hub.getInvocationStatus(pb_common.InvocationId()..value = invocationId);
+  }
+
+  /// Retained result of a succeeded detached invocation (T3). Throws
+  /// `failedPrecondition` if it is still running / failed, `notFound`
+  /// if unknown or already evicted.
+  Future<SubmitResponse> getInvocationResult(String invocationId) {
+    return _hub.getInvocationResult(pb_common.InvocationId()..value = invocationId);
+  }
+
+  /// Cancel a running detached invocation (T3). Returns true if it was
+  /// running and got signalled, false if already finished or unknown.
+  Future<bool> cancelInvocation(String invocationId) async {
+    final r =
+        await _hub.cancelInvocation(pb_common.InvocationId()..value = invocationId);
+    return r.cancelled;
+  }
+
+  pb.SubmitRequest _buildSubmitRequest({
+    required String flowYaml,
+    required Map<String, String> textInputs,
+    required Map<String, Uint8List> fileInputs,
+    required Map<String, Object?> jsonInputs,
+    required Map<String, String> fileMimeTypes,
+    bool detach = false,
+  }) {
+    final req = pb.SubmitRequest()
+      ..flowYaml = utf8.encode(flowYaml)
+      ..detach = detach;
     for (final entry in textInputs.entries) {
       req.inputs[entry.key] = pb_common.Payload()..text = entry.value;
     }
@@ -801,7 +878,7 @@ class HubClient {
       }
       req.inputs[entry.key] = pb_common.Payload()..json = _structFromMap(value);
     }
-    return _hub.submit(req);
+    return req;
   }
 
   /// Closes the gRPC channel. Idempotent.