feat(FN-2970): merge fusion/fn-2970

- CSS: fix margin on the node routing description in SettingsModal (`SettingsModal.css`)
- Dashboard: add CSS regression test for node routing description alignment (`SettingsModalNodeRouting.test.tsx`)
- Engine: update node routing policy and scheduler logic for improved routing behavior (`scheduler.ts`)
- Engine: update node routing policy tests and scheduler routing tests to cover new behavior

Commits merged:
- test(FN-2970): add CSS regression test for node routing description
- fix(FN-2970): fix settings node routing description margin
- feat(FN-2956): merge fusion/fn-2956

Files changed:
.../dashboard/app/components/SettingsModal.css     | 11 +++++++++-
 .../__tests__/SettingsModalNodeRouting.test.tsx    | 12 +++++++++--
 .../src/__tests__/node-routing-policy.test.ts      | 25 +++++++++++++++++++---
 .../src/__tests__/scheduler-node-routing.test.ts   | 18 ++++++++--------
 packages/engine/src/scheduler.ts                   |  8 ++++---
 5 files changed, 56 insertions(+), 18 deletions(-)

Fusion-Task-Id: FN-2970

packages/dashboard/app/components/SettingsModal.css

@@ -330,6 +330,15 @@
   margin-top: var(--space-xl);
 }
 
+.settings-section-description {
+  margin: 0;
+  padding: 0 var(--space-xl);
+  margin-bottom: var(--space-sm);
+  color: var(--text-muted);
+  font-size: 13px;
+  line-height: 1.5;
+}
+
 .settings-plugins-subsection-toggle {
   display: inline-flex;
   gap: var(--space-xs);
@@ -1548,7 +1557,7 @@
   border: 1px solid var(--border);
   border-radius: var(--radius-md);
   padding: var(--space-md) var(--space-lg);
-  margin-top: var(--space-lg);
+  margin-top: var(--space-sm);
   color: var(--text-muted);
   font-size: 13px;
   line-height: 1.5;

packages/dashboard/app/components/__tests__/SettingsModalNodeRouting.test.tsx

@@ -244,9 +244,17 @@ describe("SettingsModal Node Routing section", () => {
     expect(screen.queryByLabelText("Unavailable Node Policy")).not.toBeInTheDocument();
   });
 
-  it("shows informational note", async () => {
+  it("applies description and note classes for node routing spacing", async () => {
     renderModal();
     await openNodeRouting();
-    expect(screen.getByText(/These settings apply at the project level/)).toBeInTheDocument();
+
+    const descriptionText = screen.getByText(/Configure how tasks are routed to execution nodes/);
+    const noteText = screen.getByText(/These settings apply at the project level/);
+
+    expect(descriptionText).toBeInTheDocument();
+    expect(noteText).toBeInTheDocument();
+
+    expect(descriptionText.closest("p")).toHaveClass("settings-section-description");
+    expect(noteText.closest("p")).toHaveClass("settings-node-routing-note");
   });
 });