Fix plugin height and download path handling

[debpalash]

Summary

• bind active catalog/download/error cards to their explicit compact height
• normalize Qt file URLs into filesystem paths before starting a detached download
• bump the plugin to 1.4.3

Safety

• no media-write behavior changes
• target selection and erase acknowledgement remain explicit

Verification

• Omarchy manifest validation passes
• QML formatting parser and host qmllint both exit successfully