feat(studio): wire inline approval driver methods

StudioFlowRunDriver gains three new methods that satisfy the
editor 0.21.0 FlowRunDriver interface:

  - pendingApprovalIdForStep(flowName, stepId) — picks the
    newest pending approval row matching this (flow, step)
    pair from HubService.pendingApprovals().
  - approveApproval(approvalId, reviewer) — delegates to
    HubService.approve, same RPC the Approvals page uses.
  - rejectApproval(approvalId, reviewer, reason) — delegates
    to HubService.reject.

End result: when a flow run pauses on system.approval@^0,
the Run tab now renders a complete Approve / Reject form
directly under the awaiting step. Operator no longer needs
to switch tabs to make the decision; the standalone Approvals
page stays available for non-running approvals and history.

Studio bumped to 0.68.0; editor pin moves to 0.21.0.

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

lib/data/flow_run_driver.dart

@@ -120,6 +120,42 @@ class StudioFlowRunDriver implements editor.FlowRunDriver {
     return null;
   }
 
+  @override
+  Future<String?> pendingApprovalIdForStep({
+    required String flowName,
+    required String stepId,
+  }) async {
+    try {
+      final pending = await HubService.instance.pendingApprovals();
+      // Match the newest approval for this (flow, step). The hub
+      // creates one approval row per step invocation; if multiple
+      // are pending we surface the most recent (operator can still
+      // navigate to the standalone Approvals page for the others).
+      final match = pending
+          .where((p) => p.flowName == flowName && p.stepId == stepId)
+          .toList()
+        ..sort((a, b) => b.createdAt.compareTo(a.createdAt));
+      return match.isEmpty ? null : match.first.id;
+    } catch (_) {
+      return null;
+    }
+  }
+
+  @override
+  Future<void> approveApproval({
+    required String approvalId,
+    required String reviewer,
+  }) =>
+      HubService.instance.approve(approvalId, reviewer);
+
+  @override
+  Future<void> rejectApproval({
+    required String approvalId,
+    required String reviewer,
+    required String reason,
+  }) =>
+      HubService.instance.reject(approvalId, reviewer, reason);
+
   /// Studio's FlowOutput hierarchy is gRPC-shaped (one class
   /// per payload variant); the editor's is host-agnostic
   /// (text / json / bytes only). File outputs degrade to

lib/main.dart

@@ -27,7 +27,7 @@ import 'widgets/widgets.dart';
 /// Studio's own build version. Bump on every UI commit so the
 /// running app self-identifies — visible in the sidebar header
 /// and quick-glance proof that you're seeing the current build.
-const String kStudioVersion = '0.67.0';
+const String kStudioVersion = '0.68.0';
 
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();