Fix window count going out of sync when headless

[lhecker]

In headless mode, WM_CLOSE_TERMINAL_WINDOW would still decrement
_windowCount. While the count technically doesn't matter,
it going out of sync with the actual count felt wrong.

Validation Steps Performed

• TBD

[riju568]

Title

Fix: Prevent window count mismatch in headless mode

Overview

This PR resolves an issue where _windowCount was out of sync when running in headless mode. The value is not unnecessarily incremented, so it will maintain an accurate view of internal state.

Changes

• Added a check to prevent incrementing count when launching in headless mode.
• Updated related logic to maintain correct lifecycle state.
• Cleaned up unnecessary minor comments.

Related Issue

Fixes #

Testing Performed

• Launched application with the --headless flag 50+ times and confirmed _windowCount remains accurate.
• Confirmed standard UI mode behaves as normal, no issues.
• Existing features have no regressions.

Impact / Risk

Low - Change is isolated to the headless path and will not impact any potential changes to the user experience.

Checklist

• Code is inline with style standards
• No breaking changes
• Tested locally
• Ready for review