Save and restore settings window size and position - #1197

Summary

Adds window size, position, and maximized state persistence to the Settings Window across app sessions.

Motivation

Previously, opening the Settings Window always reset its size to the default 900x700 and opened at the center of the screen, discarding any resizing or repositioning done by the user.

Closes #908

Type of Change

• Feature

What Changed

• ViewModels/UserSettings.cs:
  • Added persistent properties: SettingsWindowWidth, SettingsWindowHeight, SettingsWindowLeft, SettingsWindowTop, and SettingsWindowState.
• SettingsWindow.xaml.cs:
  • Switched startup position mode to WindowStartupLocation.Manual.
  • Added GetWorkAreaForBounds(...) helper using MonitorUtil to calculate DIP-scaled work areas across multi-monitor setups.
  • Clamped target window dimensions and coordinates within the active monitor's work area, preventing the window from clipping behind taskbars or opening off-screen.
  • Centered window on initial startup (when coordinates are NaN).
  • Added listeners to LocationChanged, SizeChanged, and StateChanged to track changes while in Normal state.
  • Handled WindowState.Maximized state restoration while preserving normal restore bounds.
  • Ensured final window dimensions or RestoreBounds are flushed in SettingsWindow_Closing.

Additional Information

• Verified that multi-monitor setups with differing DPI scaling clamp coordinates cleanly within visible work areas without disappearing off-screen.
• Debounced settings serialization ensures window movement and resizing do not produce excessive disk writes.
• A user toggle in the settings UI can be introduced in a follow up PR to allow users to disable this persistence behavior if desired.

Checklist

• Code changes are manually tested and working.
• Formatting and naming are consistent with the project.
• Self-review of changes is done.

• AI tools were used (if yes, I reviewed and fully understand the changes myself).