fix(editor): ensure blur event triggers correctly in Firefox

[RohithMacharla11]

This PR fixes an issue where the Lexical editor in Firefox stays focused even after clicking outside.

Steps to Reproduce:

Open Lexical Playground in Firefox.

Type some text.

Move the cursor inside, then click outside the editor.

The editor remains focused.

Fix Implemented:

Added a mousedown listener for Firefox to detect outside clicks.

Manually dispatches BLUR_COMMAND to align behavior with Chrome/Edge.

Before:
Editor stays focused in Firefox when clicking outside.

After:
Editor correctly loses focus in Firefox when clicking outside.

Fix.mp4

[vercel]

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Project	Deployment	Preview	Comments	Updated (UTC)
lexical	Ready	Preview	Comment	Sep 5, 2025 6:52am
lexical-playground	Ready	Preview	Comment	Sep 5, 2025 6:52am

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[etrepum]

This PR contains unrelated changes that should be removed and according to the author of the issue it doesn't fix the problem #7788 (comment)