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/generated/chain/v1/hub.pbenum.dart

@@ -14,6 +14,38 @@ import 'dart:core' as $core;
 
 import 'package:protobuf/protobuf.dart' as $pb;
 
+class InvocationStatus_Phase extends $pb.ProtobufEnum {
+  static const InvocationStatus_Phase PHASE_UNKNOWN =
+      InvocationStatus_Phase._(0, _omitEnumNames ? '' : 'PHASE_UNKNOWN');
+  static const InvocationStatus_Phase PENDING =
+      InvocationStatus_Phase._(1, _omitEnumNames ? '' : 'PENDING');
+  static const InvocationStatus_Phase RUNNING =
+      InvocationStatus_Phase._(2, _omitEnumNames ? '' : 'RUNNING');
+  static const InvocationStatus_Phase SUCCEEDED =
+      InvocationStatus_Phase._(3, _omitEnumNames ? '' : 'SUCCEEDED');
+  static const InvocationStatus_Phase FAILED =
+      InvocationStatus_Phase._(4, _omitEnumNames ? '' : 'FAILED');
+  static const InvocationStatus_Phase CANCELLED =
+      InvocationStatus_Phase._(5, _omitEnumNames ? '' : 'CANCELLED');
+
+  static const $core.List<InvocationStatus_Phase> values =
+      <InvocationStatus_Phase>[
+    PHASE_UNKNOWN,
+    PENDING,
+    RUNNING,
+    SUCCEEDED,
+    FAILED,
+    CANCELLED,
+  ];
+
+  static final $core.List<InvocationStatus_Phase?> _byValue =
+      $pb.ProtobufEnum.$_initByValueList(values, 5);
+  static InvocationStatus_Phase? valueOf($core.int value) =>
+      value < 0 || value >= _byValue.length ? null : _byValue[value];
+
+  const InvocationStatus_Phase._(super.value, super.name);
+}
+
 class HealthStatus_State extends $pb.ProtobufEnum {
   static const HealthStatus_State UNKNOWN =
       HealthStatus_State._(0, _omitEnumNames ? '' : 'UNKNOWN');