FN-5831: guard branchContext group chip rendering in TaskCard

Fix TaskCard branch group chip logic to satisfy strict branchContext nullability checks.

- Replace optional chaining-only guard with explicit branchContext and groupId presence checks
- Hoist group metadata into local constants to avoid repeated nullable property access
- Keep shared/group chip title, label, click handling, and displayed value behavior unchanged while type-safe

Files changed:
 packages/dashboard/app/components/TaskCard.tsx | 46 +++++++++++++-------------
 1 file changed, 23 insertions(+), 23 deletions(-)

Fusion-Task-Id: FN-5831

Fusion-Task-Lineage: 65e2c335-3884-42ba-b87e-5e6a9e0245d8

packages/dashboard/app/components/TaskCard.tsx

@@ -1894,30 +1894,30 @@ function TaskCardComponent({
               <span className="card-branch-value">{branchMetadata.baseBranch}</span>
             </span>
           )}
-          {task.branchContext?.groupId && (
-            <span
-              className="card-branch-chip"
-              title={
-                task.branchContext.assignmentMode === "shared" && branchMetadata.branch
-                  ? `${task.branchContext.groupId} · ${branchMetadata.branch}`
-                  : task.branchContext.groupId
-              }
-              onClick={(event) => {
-                if (!onOpenGroupModal) return;
-                event.stopPropagation();
-                onOpenGroupModal(task.branchContext.groupId);
-              }}
-            >
-              <span className="card-branch-label">
-                {task.branchContext.assignmentMode === "shared" ? "Shared" : "Group"}
+          {task.branchContext != null && task.branchContext.groupId != null && (() => {
+            const groupId = task.branchContext.groupId;
+            const isSharedAssignment = task.branchContext.assignmentMode === "shared";
+            return (
+              <span
+                className="card-branch-chip"
+                title={
+                  isSharedAssignment && branchMetadata.branch
+                    ? `${groupId} · ${branchMetadata.branch}`
+                    : groupId
+                }
+                onClick={(event) => {
+                  if (!onOpenGroupModal) return;
+                  event.stopPropagation();
+                  onOpenGroupModal(groupId);
+                }}
+              >
+                <span className="card-branch-label">{isSharedAssignment ? "Shared" : "Group"}</span>
+                <span className="card-branch-value">
+                  {isSharedAssignment && branchMetadata.branch ? branchMetadata.branch : groupId}
+                </span>
               </span>
-              <span className="card-branch-value">
-                {task.branchContext.assignmentMode === "shared" && branchMetadata.branch
-                  ? branchMetadata.branch
-                  : task.branchContext.groupId}
-              </span>
-            </span>
-          )}
+            );
+          })()}
         </div>
       )}
       {showProgressSection && (() => {