fix(desktop): resolve window maximize, titlebar interactions, and keyboard shortcut leaks

[AI-fullcup]

This PR bundles three closely related fixes in the Electron main process and window interactions.

Fixes #99: Titlebar double-click maximize behavior

Problem:

• Double-clicking interactive buttons (navigation, search, settings, avatar) in the topbar accidentally toggles window maximize because the event bubbles up to TopbarDesktop's onDoubleClick handler.
• Conversely, double-clicking the empty titlebar area was often unresponsive because app-region-drag swallows events on Windows frameless windows, while the fallback onDoubleClick only fires on app-region-no-drag children.
• Under the hood, the restore logic in ipcMain.ts had the width/height swapped and passed width twice to setSize().

Changes:

• TopbarDesktop.tsx: Added e.stopPropagation() on the left and right interactive containers so button double-clicks no longer maximize the window.
• ipcMain.ts: Fixed unMaximizeSize = { width: size[0], height: size[1] } (was size[1], size[0]) and corrected win.setSize(width, height).

Fixes implicit bug: Broken maximize state synchronization

Problem:
ipcMain.ts manually tracked isMaximized with a local boolean. This easily desynchronizes when the user maximizes the window via OS shortcuts (e.g. Win+↑) or edge snapping. The stale state then caused wrong restore behavior and confusing IPC replies.

Changes:

• Replaced the manual isMaximized variable with win.isMaximized() everywhere.
• Removed the erroneous isMaximized = !isMaximized inside MinimizeOrUnminimize; minimizing a window has nothing to do with its maximized state and was corrupting the UI.

Fixes #74: Global keyboard shortcuts failing and leaking memory

Problem:

• keyboardShortcuts.ts added focus/blur listeners on win but attempted to remove them from webContexts, so they were never unregistered. Every window recreate leaks two listeners on the main process, eventually making shortcuts sluggish or dead.
• formatForAccelerator() can return null, but the code used a non-null assertion (!) and fed it straight into globalShortcut.register(null), which throws an uncaught exception and can kill the shortcut subsystem.

Changes:

• Corrected removeListener target from webContexts to win.
• Introduced safeRegister() with explicit null checks and try/catch around every globalShortcut.register call.

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Testing notes:

• Window maximize/restore via titlebar double-click and window controls works correctly on Windows.
• Restored window dimensions match the pre-maximize size.
• Global shortcuts can be toggled and rebound without leaking listeners or crashing the main process.