Update skills CLI upgrade command

fix: update actions/checkout version to v5 in workflow files

feat: add support section to README with GitHub Sponsors link for ongoing maintenance

feat: add scripts for syncing and validating issue templates; update issue template labels

fix: update platform badge in README and format code blocks for clarity

feat: add auto-assign workflow for newly opened issues

fix: update labels and descriptions in skill content bug template for clarity

feat: add issue templates for skill requests, content bugs, and enhancements; implement sync script for dropdowns

feat: update all skills to Swift 6.3

docs(changelog): add audit fixes to v3.0.0 release notes

docs(readme): clarify instructions for installing themed bundles

fix(docs): update descriptions and improve clarity in SKILL.md files

fix(ios-networking): remove broken reference to background-websocket.md

docs(references): add Contents sections to three reference files

fix(widgetkit): IntentTimelineProvider is not deprecated