fix: restore settings window resizing

[jatinkrmalik]

Summary

• Restore the Settings window's AppKit resizable style mask.
• Let the SwiftUI settings content grow from its existing minimum size instead of forcing an exact size.
• Align the initial window content height with the settings view's minimum height.

Root cause

The custom settings NSWindow was created without .resizable, and the root SettingsView used an exact fixed frame. Together, that removed the resize affordance and prevented the settings content from expanding.

Validation

• swift build
• swift test (224 tests, 1 skipped, 0 failures)