FN-6147: polish simple editor mobile button states

Polish simple workflow editor controls for clearer mobile interaction.

- add hover, focus, and active states to simple editor graph buttons and mobile tab/add controls
- replace hard-coded simple editor spacing with shared spacing tokens for node labels and edge chips
- add CSS contract tests covering the new button state and spacing rules

Files changed:
 .../app/components/MobileWorkflowGraphView.css     |  57 +++++++++++-
 .../app/components/WorkflowNodeEditor.css          |  37 ++++++++
 .../__tests__/MobileWorkflowGraphView.css.test.ts  | 100 +++++++++++++++++++++
 3 files changed, 191 insertions(+), 3 deletions(-)

Fusion-Task-Id: FN-6147

Fusion-Task-Lineage: 5ef4baeb-ccad-4811-aada-a195ecf8d754

packages/dashboard/app/components/WorkflowNodeEditor.css

@@ -1484,6 +1484,10 @@
     background: var(--bg-secondary);
     color: var(--text);
     cursor: pointer;
+    transition:
+      background var(--transition-fast),
+      transform var(--transition-fast),
+      box-shadow var(--transition-fast);
   }
 
   .wf-mobile-tab--active {
@@ -1491,6 +1495,19 @@
     background: var(--bg-tertiary);
   }
 
+  .wf-mobile-tab:hover {
+    background: var(--bg-tertiary);
+  }
+
+  .wf-mobile-tab:focus-visible {
+    outline: none;
+    box-shadow: var(--focus-ring-strong);
+  }
+
+  .wf-mobile-tab:active {
+    transform: scale(0.97);
+  }
+
   .wf-mobile-panel {
     flex: 1 1 auto;
     min-height: 0;
@@ -1541,6 +1558,26 @@
     cursor: pointer;
     text-align: left;
     overflow-wrap: anywhere;
+    transition:
+      background var(--transition-fast),
+      transform var(--transition-fast),
+      box-shadow var(--transition-fast);
+  }
+
+  .wf-mobile-add-option:hover,
+  .wf-mobile-template-option:hover {
+    background: var(--bg-tertiary);
+  }
+
+  .wf-mobile-add-option:focus-visible,
+  .wf-mobile-template-option:focus-visible {
+    outline: none;
+    box-shadow: var(--focus-ring-strong);
+  }
+
+  .wf-mobile-add-option:active,
+  .wf-mobile-template-option:active {
+    transform: scale(0.97);
   }
 
   .wf-mobile-template-filter {