feat: optimization async, style extract, dom manipulation

[BRama10]

Great work @richards199999 !

This PR maintains same functionality, just optimizes & makes the plugin a bit more extensible.

Key changes made:

• Cached selectors in static constants, so that we can extend them globally or in scopes without needing to modify the internal structure
• Reduced redundant DOM traversals
• Used a single observer instance with debouncing since the earlier multiple even listeners could result in memory leaks
• Proper timeout cleanup as well as async formats and process queue management

[richards199999]

LGTM!