fix:Emmet expands abbrevations when text is pasted

[Nishthajain7]

Issue:

Fixes #3872

Demo:

Screencast.from.2026-02-22.14-49-21.webm

Changes:

Added a paste event handler to trigger expandAbbreviation when content is pasted.

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• has no typecheck errors (npm run typecheck)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123
• meets the standards outlined in the accessibility guidelines