Migrated the entire interface to extUI v0.3.0, replacing all hand-rolled DOM and custom CSS with the shared component library for a consistent dark/OLED design across every surface.

UI Migration
- Popup rebuilt with ExtUI.Popup, ExtUI.createStatsGrid, and ExtUI.createQuickActions.
- Dashboard rebuilt with ExtUI.Dashboard, ExtUI.TabPanel, and ExtUI.createSettingRow — all settings now use the library's toggle and number input controls.
- Suspended tab page uses extUI button and card components.
- Whitelist management moved to ExtUI.SortableList with drag-to-reorder and per-item remove buttons.

My Extensions Tab
- New dedicated dashboard tab that lists the developer's other published AMO add-ons, fetched live via the AMO REST API.
- Uses ExtUI.createAddonList to render each add-on as a card with icon, name, description, star rating, and user count.
- Fetches the developer's AMO profile (avatar, display name, bio) and shows it in a header with a link to the full profile.
- Shows skeleton loading state while data is being fetched.
- Added host_permissions for addons.mozilla.org to support API requests.

Fixes
- Fixed a syntax error in the extUI library's accent colour computation that prevented the entire library from loading.
- Popup initialisation wrapped in DOMContentLoaded to eliminate the "layout forced before page was fully loaded" console warning.