🧹 remove unused variable lastHoveredElement from selector-capture.js

[cmuench]

This PR removes the unused variable lastHoveredElement from the content-scripts/selector-capture.js file.

🎯 What: The lastHoveredElement variable was declared and assigned in several event handlers but its value was never used for any logic or state management.
💡 Why: Removing dead code and unused state variables improves the overall maintainability and readability of the codebase.
✅ Verification:

• Manually verified the removal of all occurrences using grep.
• Ran relevant unit tests (npm test tests/sendWebhook.test.js tests/security.test.js) which passed.
• Other tests failed due to environmental issues (missing jsdom) unrelated to this change.
  ✨ Result: A cleaner and more focused selector-capture.js script.

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PR created automatically by Jules for task 10890858407383467354 started by @cmuench

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