feat(macos): refresh recommendations with Command+R

[xiejiaxue]

Changes

• Add a macOS-only Command + R keyboard shortcut for refreshing recommendations
• Register the shortcut at the main app level so it works regardless of the current focus node
• Only refresh when the Home navigation and Recommendation tab are active
• Reuse the existing recommendation refresh flow

Why

Provide the standard macOS refresh shortcut for quickly reloading recommendation content.

Validation

• fvm flutter analyze lib/pages/home/view.dart lib/pages/main/controller.dart lib/pages/main/view.dart
• fvm flutter build macos --debug with the repository-required Flutter patches applied
• Launched the generated macOS debug app locally
• Pressed Command + R on the Recommendation page and confirmed that new recommendation cards loaded
• git diff --check

All checks passed.