chore(types): re-add type-only BrowserWindow / Tray imports

Follow-up to the CJS refactor: destructuring electron.BrowserWindow /
electron.Tray pulled the values into scope but lost the type
namespace, breaking sites that used the bare class name as a type
(let win: BrowserWindow | null, return-type annotations,
implicitly-any close handlers). Added 'import type { ... as ...Type }'
for each affected file and replaced the type-position references
with the aliased names. Runtime semantics unchanged; typecheck
exits 0 again.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/main/windows/inboxWindow.ts

@@ -1,16 +1,17 @@
 import electron from 'electron';
+import type { BrowserWindow as BrowserWindowType } from 'electron';
 const { BrowserWindow, app } = electron;
 import { join } from 'node:path';
 import { fileURLToPath } from 'node:url';
 
-let inboxWindow: BrowserWindow | null = null;
+let inboxWindow: BrowserWindowType | null = null;
 const __dirname = fileURLToPath(new URL('.', import.meta.url));
 
-export function getInboxWindow(): BrowserWindow | null {
+export function getInboxWindow(): BrowserWindowType | null {
   return inboxWindow;
 }
 
-export function createInboxWindow(): BrowserWindow {
+export function createInboxWindow(): BrowserWindowType {
   if (inboxWindow && !inboxWindow.isDestroyed()) {
     inboxWindow.show();
     inboxWindow.focus();