feat(desktop): add auto-zoom scaling for high-DPI displays

[SuperComboGamer]

Windows does not automatically scale Electron app content for high-DPI displays the way macOS does, causing the app to
appear tiny on 4K/1440p monitors. This adds automatic zoom scaling to fix that.

• Auto-detect display resolution and scale the desktop app UI for 4K/1440p monitors while keeping 1080p unchanged
• Compute zoom factor from the display's DIP short edge relative to 1080p, snapped to 0.25 increments (max 3.0×)
• Apply zoom on window creation, display change, move/resize across monitors, unmaximize, and leave-fullscreen
• Clamp window bounds and minimum size to the display work area after zoom changes
• Replace built-in viewMenu with custom View menu fixing Ctrl++ (zoom in) , and adding Ctrl+0 to reset to
  auto-zoom baseline
• Re-entrancy guards prevent recursive setBounds → move loops; fullscreen/maximized states are skipped
• On macOS the auto-zoom is a no-op since macOS handles HiDPI scaling natively

Note

Add auto-zoom scaling for high-DPI displays in the desktop app

• On Windows and Linux, the app now computes a zoom factor based on the display's short edge relative to a reference size, scaling up for high-resolution displays; macOS always uses zoom factor 1.0.
• Zoom In/Out menu actions adjust a persisted delta stored in a JSON preferences file, so user zoom preference survives restarts.
• Reset Zoom clears the stored delta and recomputes zoom from display metrics.
• Windows opened or moved to a different display recompute their zoom, minimum size, and on-screen bounds to fit the new display's work area.
• Behavioral Change: window minimum size and bounds are now clamped to the display work area when not maximized or fullscreen; display metric changes (e.g. resolution/DPI changes) clear any user zoom delta on Windows/Linux.

^{Macroscope summarized 27ca07a.}

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[t3dotgg]

Couple Qs:

1. If I set a zoom myself, will this override it?
2. Is this windows-only? Can it be?
3. How does it handle multiple monitors? Esp. if I have some that are HighDPI and others that are not

[SuperComboGamer]

@t3dotgg

If I set a zoom myself, will this override it?
No. Your manual zoom (Ctrl+= / Ctrl+-) is persisted and respected, I added zoom persistence in this PR since Electron doesn't have it built-in. Auto-zoom won't override it. Ctrl+0 resets back to auto.

Is this windows-only? Can it be?
Auto-zoom is Windows + Linux only. macOS is skipped since Retina handles DPI natively. Zoom persistence works on all platforms.

How does it handle multiple monitors?
Zoom is stored as a delta from each display's auto-computed, baseline not an absolute value. So if you bump zoom by +0.25 on a 4K monitor (auto 2.0 → 2.25), dragging to a 1080p monitor gives you 1.0 + 0.25 = 1.25, not 2.25. Your intent (“slightly bigger than default”) transfers correctly across displays.

Note: I don't have a Mac or Linux machine so I couldn't test on those platforms, but it should work, macOS just skips auto-zoom entirely and the zoom persistence uses standard Electron/Node APIs.

[SuperComboGamer]

Closes #861