Simple Dark Mode - Eye care από Athar

Toggle dark mode for the current site from the popup or right‑click context menu.
Remembers preference per domain via storage.
Lightweight: no network requests, no tracking, no external scripts.
Permissions used:
storage: save per‑site on/off
activeTab: message the current tab
contextMenus: add “Toggle Dark Mode” item
MV2 background script; content script applies CSS invert + hue‑rotate filter.