fix(settings): clean up Windows UI resources

[laceyp99]

Summary

• use the canonical AppData directory for generated icons and set Murmur's Windows identity before other UI is created
• give settings variables explicit window ownership and release native icon handles when each settings window closes
• restore shared Tk window-class icon handles before releasing settings-window native handles, including the icon-photo failure path
• remove the related settings and logging maintenance traps, with focused regression coverage

Closes #36.

Validation

• venv\\Scripts\\ruff.exe format --check .
• venv\\Scripts\\ruff.exe check .
• venv\\Scripts\\pytest.exe -q (172 passed)
• GitHub CI: guardrails and Ubuntu/Windows test jobs passed

Notes

• No packaging, install, or CI behavior changes.
• Automated tests cover icon ownership, shared-class restoration, and cleanup; repeated real-window open/close behavior was not manually exercised.
• Follow-up issue #48 tracks packaging Murmur as a named Windows executable with embedded icon and version metadata. The current PR can merge independently.

[laceyp99]

Validation

• Full test suite: venv\Scripts\pytest.exe -q — 172 passed.
• ruff format --check, ruff check, and git diff --check passed; GitHub Ubuntu and Windows CI passed.
• On Windows, confirmed %APPDATA%\murmur\murmur.ico was generated and the icon looked correct at native size in the Settings title bar, taskbar, Alt+Tab, and system tray.
• Closed and reopened the app more than 10 times; the tray and Settings GUI remained responsive.
• Verified settings persistence: closing without saving discarded the change; saving persisted it after reopen; the original value was restored.

Notes

Task Manager showed Python processes rather than a searchable Murmur identity, which is not a reliable AppUserModelID check for this tray-resident app; taskbar, title bar, Alt+Tab, and tray behavior were correct. The forced native icon-photo failure path is covered by mocked tests only and was not manually induced.