Fixes only, no new features.

Sites that still won:
- Content wrapped in a block marked "not editable" stayed locked.
- Blocks re-applied through less common methods got through.
- Aggressive mode did not unblock pasting when the site set the handler on the field.
- A site shown inside another site's page stayed locked.

Things the extension shouldn't have done:
- A site's own "copy snippet" button copied your previous selection instead.
- Turning "Text selection and copy" off still stripped handlers from pages.
- Relocking didn't fully undo itself, and sometimes left the page selectable.

Settings:
- If settings couldn't be read while you flipped a switch, every open tab was reset
to the defaults. It now leaves your pages alone.
- The settings page could show a switch it never saved, and could report "None yet"
when it simply couldn't read your saved sites.
- Permission granted for a site that then failed to save is now handed straight back.