fix(FN-2634): remove surface-hover fallback usage in dashboard CSS

- Replace hover background fallbacks with direct var(--surface-hover) in QuickChatFAB and SettingsModal styles
- Tighten status-colors theme test to forbid var(--surface-hover, ...) fallback syntax
- Preserve token-based hover styling contract while preventing stale fallback patterns from reappearing

packages/dashboard/app/__tests__/status-colors-theme.test.ts

@@ -101,8 +101,9 @@ describe("Status color CSS custom properties", () => {
     expect(css).not.toMatch(/--surface-(subtle|muted|emphasis|hover-strong):\s*rgba\(/);
   });
 
-  it("uses --surface-hover token references without raw rgba fallbacks", () => {
+  it("uses --surface-hover token references without fallbacks", () => {
     expect(css).toContain("var(--surface-hover)");
+    expect(css).not.toMatch(/var\(--surface-hover,\s*/);
     expect(css).not.toMatch(/var\(--surface-hover,\s*rgba\(/);
   });
 

packages/dashboard/app/components/QuickChatFAB.css

@@ -276,7 +276,7 @@
 }
 
 .quick-chat-message-render-toggle:hover {
-  background: var(--surface-hover, color-mix(in srgb, var(--surface) 70%, transparent));
+  background: var(--surface-hover);
   color: var(--text);
 }
 

packages/dashboard/app/components/SettingsModal.css

@@ -193,7 +193,7 @@
 }
 
 .settings-plugins-subsection-btn:hover {
-  background: var(--surface-hover, color-mix(in srgb, var(--text-muted) 8%, transparent));
+  background: var(--surface-hover);
   color: var(--text);
 }