Expose initialFocus prop on Modal component (passthrough to Headless
UI Dialog) so the create blank skill modal reliably focuses the name
input when opened, replacing the ineffective autoFocus attribute.
Wire up the "Create Blank Skill" action card to open a modal where
users enter a skill name. The modal validates against existing skill
names in real-time and creates a folder with a SKILL.md file via
batchUpload, then opens the file as a pinned tab.