[v0.9.1] Scale every code-built dialog with the display

[JUhalt]

Found

The maintainer saw Download & Restart cut off in the update prompt (fixed for v0.8.0 in #90). The cause is general: code-built dialogs set AutoScaleMode.Dpi without AutoScaleDimensions, so at 125% and 150% their text grows with the display while their fixed sizes do not. Before v0.8.0 only About had base dimensions; the update prompt and progress window now do as well. 45 other forms still set AutoScaleMode.Dpi without them.

Most look right because their controls size to their text or scale explicitly with UiTheme.Px. Others are cramped: at 150% the Route View opens at its 96-DPI size (1040×800 pixels), so the route map card uses its one-column key. Simply adding base dimensions everywhere would double-scale dialogs that already scale by hand, and a dialog scaled to 150% can outgrow the screen (the Route View would be 1200 pixels tall on a 1003-pixel working area).

Scope

• Audit each code-built form at 100%, 125%, and 150%: record whether it scales by AutoScaleDimensions, by UiTheme.Px, or not at all.
• Settle one rule, for example: base dimensions of 96 DPI on every form, no hand scaling inside forms that have them, and every initial size capped to the working area of the screen it opens on.
• Add a test that constructs every form at a simulated 150% and checks that no button's preferred width exceeds its actual width, and that each form fits a 1366×728 working area.

Acceptance

• Every dialog opens fully visible, with complete button labels, at 100%, 125%, and 150% (evidence per dialog in [v0.9.1] Workflow hardening and 1.0 preparation tracker #43).

[JUhalt]

Found during the v0.9 check at 150% (#97): Preferences (SettingsForm, ClientSize 780×760, no AutoScaleDimensions) opens at about its 125% pixel size on a 150% screen. Everything fits and its content scrolls, but v0.9 added the Online services and AI assistant cards to it, so it now holds a lot in a small window. When it is scaled, check the buttons whose minimum sizes are computed with UiTheme.Px(…, DeviceDpi) so they are not scaled twice.