FN-6144: make mobile node editor inspector fill available height

Let the mobile workflow node editor use the full available screen height.

- replace the mobile inspector max-height cap with flex sizing so the editor stage can expand full screen
- preserve mobile inspector scrolling by setting a zero min-height in the stacked layout
- update the mobile CSS contract test to assert the new flex-based sizing rules

Files changed:
 packages/dashboard/app/components/WorkflowNodeEditor.css               | 3 ++-
 .../dashboard/app/components/__tests__/WorkflowNodeEditor.css.test.ts  | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

Fusion-Task-Id: FN-6144

Fusion-Task-Lineage: 49d06acb-17c6-40fd-9c6d-3af98ddf8f6e

packages/dashboard/app/components/WorkflowNodeEditor.css

@@ -1398,7 +1398,8 @@
   .wf-editor-body--editor-stage .wf-editor-inspector {
     width: 100%;
     min-width: 0;
-    max-height: 45vh;
+    flex: 1 1 auto;
+    min-height: 0;
     border-left: none;
     border-top: 1px solid var(--border);
     overflow-y: auto;