fix: move to container shows proper containers now

[croossin]

Fix "Move to Container" context menu functionality

Context menu not showing containers:

• Fixed condition that was incorrectly comparing against activeContainer instead of checking if each container differs from the tab's current container
• Fixed action callback that was passing the tab's current container instead of the target container

Emoji display in context menu:

• Replaced Label with custom text icons (which don't render properly in macOS context menus) with simple string interpolation
• Made emoji display conditional - only shows if container has an emoji set

UX improvements:

• Hide "Move to Container" option entirely when only one container exists
• Clean up dividers to avoid orphaned separators

Before

CleanShot.2025-09-27.at.07.33.31.mp4

After

CleanShot.2025-09-27.at.07.32.54.mp4