FN-5673: keep mobile nav and footer pinned when keyboard opens

Prevent keyboard viewport shifts from displacing mobile bottom bars while preserving iOS hide safeguards.

- Split executor footer keyboard behavior into separate hide and pinning controls
- Add keyboard-open CSS overrides to keep mobile nav/footer bottom at 0 instead of offsetting upward
- Wire App to pass distinct keyboard props and expand component/CSS contract tests for keyboard-open classes and rule ordering

Files changed:
 packages/dashboard/app/App.tsx                     |  3 ++-
 packages/dashboard/app/__tests__/mobile-bottom-bars-keyboard-layout.test.ts | 30 ++++++++++++++++++++++
 packages/dashboard/app/components/ExecutorStatusBar.css |  6 +++++
 packages/dashboard/app/components/ExecutorStatusBar.tsx | 14 +++++-----
 packages/dashboard/app/components/MobileNavBar.css |  3 ++-
 packages/dashboard/app/components/__tests__/ExecutorStatusBar.test.tsx | 17 ++++++++++++
 packages/dashboard/app/components/__tests__/MobileNavBar.test.tsx |  6 +++--
 7 files changed, 69 insertions(+), 10 deletions(-)

Fusion-Task-Id: FN-5673

Fusion-Task-Lineage: 7c2dc749-214a-48ab-af58-5638ea27ae47

packages/dashboard/app/components/ExecutorStatusBar.css

@@ -298,6 +298,12 @@
     bottom: calc(var(--icb-bottom-offset, 0px) + var(--mobile-nav-height) + max(env(safe-area-inset-bottom, 0px), 12px) + var(--standalone-bottom-gap));
   }
 
+  /* Keyboard-open override: ignore ICB offset so the keyboard can cover the
+     footer instead of displacing it upward by keyboard height. */
+  .executor-status-bar.executor-status-bar--keyboard-open {
+    bottom: 0;
+  }
+
   .executor-status-bar__segment {
     min-width: 0;
     gap: 4px;