Fix responsive window layout and DPI-scaled controls

[EdnLove]

What changed

• Restore window dimensions safely across monitors and DPI scales.
• Prevent maximized dimensions from being persisted as normal window dimensions.
• Force NavigationView content and CleanerPage panels to stretch and shrink correctly.
• Remove fixed button heights from the Cleaner page so Analyze, Cancel, and Run Cleaner adapt to larger system text/DPI scaling.
• Add the missing FluentCleaner.Tools model definitions required by ToolsPage.

Why

On high-DPI/maximized displays, the bottom action buttons were clipped and the project did not compile because ToolsPage referenced missing model types.

Validation

• Built with .NET SDK 10.0.301 using Release/x64.
• Result: 0 errors; existing warnings remain in NewCleanerDialog.xaml.cs and Windows App SDK resource generation.
• Verified the maximized desktop window and confirmed the action button labels render completely.