Add visual feedback for profile and binding changes

[Focus2321]

Summary

• mark the active profile with a native menu checkmark
• show brief confirmations after keyboard binding and profile changes
• show the bound application's cached icon in binding confirmations
• size the feedback HUD to its icon and message
• replace an in-flight confirmation and restart its dismissal timer

Why

Keyboard-driven configuration currently gives little confirmation that a binding or profile change succeeded. The lightweight HUD does not activate Reef, become key, accept mouse events, or add work to normal switching and cycling.

Validation

• git diff --check
• unsigned macOS xcodebuild test -only-testing:ReefTests

Closes #47

[Focus2321]

Changes were made using CODEX, but everything was manually tested.

Binding Changes

Profile Changes