AMO-Safe Skeleton wót JBO

AMO-Safe is a small, AMO-friendly extension skeleton. AMO-Safe demonstrates best practices required by Mozilla's add-on policies: it requests only the storage and activeTab permissions, keeps all JavaScript in external files (no inline scripts), avoids unsafe DOM APIs such as innerHTML, and never loads or executes remote code. The popup provides a safe action to copy the current page's title to the clipboard and to inject a compact content script on user gesture for highlighting the currently selected element. The options page stores a user-configurable highlight color in browser.storage.