Handle Package and Channel filtering left side viewport overflow

[RRosio]

The FilterPopover is positioned with "right: 0" which aligns it to the right edge of its parent. However, there's no handling for cases where the popover might overflow the viewport on the left side, especially on smaller screens or when the parent is near the right edge. Consider adding logic to dynamically position the popover or use max-width constraints based on viewport size to prevent layout issues.

Originally posted by @Copilot in https://github.com/mamba-org/gator/pull/370#discussion_r2621305153