Fix WinUI workspace and editor interactions

[puppyben1]

Summary

• fix workspace tree expansion state and lazy loading
• prevent editor formatting and workbench timers from causing UI event loops
• apply theme-correct editor syntax colors
• suppress Git child console windows and defer Git file click work to avoid XAML reentrancy
• filter internal Git changes from workspace refreshes

Verification

• WinUI x64 Release build succeeds with 0 warnings and 0 errors
• verified idle CPU and memory remain stable
• verified file input and tab switching remain responsive