feat: detached-runs monitor page (T3 parity)

New Runs sidebar destination listing detached invocations (detach:true)
with phase, current step, project and a Cancel button while
pending/running. Workspace-scoped like Audit/Approvals, polls every 2s.
Detached runs are opt-in (detached.enabled) — the empty state explains
how to enable them. Inline help doc DE+EN. DetachedRun model +
listDetachedRuns/cancelDetachedRun in HubService, backed by the SDK's
listInvocations()/cancelInvocation(). flutter analyze clean; 29 tests
green (sidebar Y-stability updated for the new destination, model
mapping unit-tested).

Screenshot verification (light+dark) deferred — shared desktop in use.

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

test/detached_run_test.dart

@@ -0,0 +1,96 @@
+// DetachedRun model — the phase mapping + cancellable predicate that
+// drive the runs monitor's chip tone and the cancel-button visibility.
+
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:chain_studio/data/hub.dart';
+// The generated enum type isn't re-exported by the SDK's public
+// surface (only the message typedefs are), so build fixtures against
+// the generated file directly — test-only.
+import 'package:chain_client_sdk/src/generated/chain/v1/hub.pb.dart';
+
+InvocationEntry _entry({
+  required String id,
+  required int phaseValue,
+  String flow = 'demo',
+  String project = 'general',
+  String step = '',
+  String error = '',
+}) {
+  final status = InvocationStatus()
+    ..phase = InvocationStatus_Phase.valueOf(phaseValue)!
+    ..currentStep = step
+    ..startedAt = '2026-07-12T10:00:00Z'
+    ..error = error;
+  return InvocationEntry()
+    ..invocationId = id
+    ..flowName = flow
+    ..project = project
+    ..status = status;
+}
+
+void main() {
+  test('maps each wire phase to the model phase', () {
+    expect(
+      DetachedRun.fromEntry(_entry(id: 'a', phaseValue: 1)).phase,
+      DetachedPhase.pending,
+    );
+    expect(
+      DetachedRun.fromEntry(_entry(id: 'b', phaseValue: 2)).phase,
+      DetachedPhase.running,
+    );
+    expect(
+      DetachedRun.fromEntry(_entry(id: 'c', phaseValue: 3)).phase,
+      DetachedPhase.succeeded,
+    );
+    expect(
+      DetachedRun.fromEntry(_entry(id: 'd', phaseValue: 4)).phase,
+      DetachedPhase.failed,
+    );
+    expect(
+      DetachedRun.fromEntry(_entry(id: 'e', phaseValue: 5)).phase,
+      DetachedPhase.cancelled,
+    );
+    expect(
+      DetachedRun.fromEntry(_entry(id: 'f', phaseValue: 0)).phase,
+      DetachedPhase.unknown,
+    );
+  });
+
+  test('only pending and running runs are cancellable', () {
+    expect(
+      DetachedRun.fromEntry(_entry(id: 'a', phaseValue: 1)).isCancellable,
+      isTrue,
+    );
+    expect(
+      DetachedRun.fromEntry(_entry(id: 'b', phaseValue: 2)).isCancellable,
+      isTrue,
+    );
+    for (final terminal in [3, 4, 5]) {
+      expect(
+        DetachedRun.fromEntry(_entry(id: 'x', phaseValue: terminal))
+            .isCancellable,
+        isFalse,
+      );
+    }
+  });
+
+  test('carries flow name, project, step and error through', () {
+    final run = DetachedRun.fromEntry(
+      _entry(
+        id: 'inv-1',
+        phaseValue: 4,
+        flow: 'intake',
+        project: 'client-a',
+        step: 'extract',
+        error: 'boom',
+      ),
+    );
+    expect(run.id, 'inv-1');
+    expect(run.flowName, 'intake');
+    expect(run.project, 'client-a');
+    expect(run.currentStep, 'extract');
+    expect(run.error, 'boom');
+    expect(run.startedAt, isNotNull);
+  });
+}