fix:clear request selection when closing details pane

[aasifa1]

Closes #51

📜 Summary of changes:

Fixed an issue where a request row remained highlighted in the network table after closing the request details pane.

The table selection is now controlled by the currently open request. When the details pane is closed, the selected request is cleared and the row is no longer highlighted.

🎥 Demo Video:

Video/Demo: Not available — UI verification could not be completed locally because the desktop interception environment could not be launched.

✅ Checklist:

• Make sure linting and unit tests pass.
• No install/build warnings introduced.
• Verified UI in browser.
• For changes in extension's code, manually tested in Chrome and Firefox.
• Added/updated unit tests for this change.
• Raised pull request to update corresponding documentation (if already exists).
• Added demo video showing the changes in action (if applicable).

🧪 Test instructions:

1. Open the network traffic table.
2. Select a request to open its details pane.
3. Close the request details pane.
4. Verify that the previously selected request row is no longer highlighted.

Automated validation:

• TypeScript type-check passes.
• 37 existing tests pass.
• git diff --check passes.
• Core build passes.

🔗 Other references:

Issue #51

[CLAassistant]

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