fix: make the expanded main window resizable

[MataM15]

Summary

Draft: allow resizing the expanded main window without leaving compact mode in a large empty window. This independent contribution is based on upstream main; candidate commit: 1ca4c45.

Related Issue

No exact resizing issue identified. This does not implement saved window positioning or persisted window dimensions.

Changes

• Add an explicit lower-right resize grip and manual expanded-window sizing with minimum dimensions.
• Constrain layout width and provide bounded body scrolling while keeping footer controls reachable.
• Preserve compact auto-sizing and remember the expanded size only for the current application session.
• Handle localized footer direction and maximized restore bounds without changing optimization logic.

Checklist

• My code follows the project’s coding style and conventions.
• I have tested the changes locally.
• I have updated documentation if necessary. No new persisted setting is introduced.
• This PR does not introduce any breaking changes.
• I have added unit tests if applicable. Interactive validation remains pending.

Additional Notes

Standalone hosted Windows validation: Release/WPF build with 0 warnings and 0 errors. This is build evidence only, not a claim of interactive UI testing.

Keep this PR as a draft until checking pointer resizing, scrolling at minimum size, compact/expanded transitions, RTL, high-DPI layouts, and maximized-window behavior on Windows. No new exclusion-description localization key is required by this branch. No cleanup policy, fork-only workflow, benchmark, or packaging changes are included. Scope: 2 UI files, 226 changed lines.