Electron app loading improvements + Windows paths fix (#429)

- Electron no longer allows Windows paths in URLs
(https://www.electronjs.org/docs/latest/breaking-changes#behavior-changed-custom-protocol-url-handling-on-windows),
fixes with help of wabac.js to replace `C:\path\to\file` with
`C//path/to/file`
- Electron app cleanup: replace deprecated protocol handlers with new
protocol.handle() method, update types
- Electron app: ensure just filename is displayed on index page,
consistent with other platforms
- Update to wabac.js 2.23.2
- Update to Electron 36.3.2
- Fixes #427
- bump to 2.3.12

playwright.config.js

@@ -6,15 +6,15 @@ export default defineConfig({
   projects: [
     {
       name: "chrome",
-      use: { ...devices['Desktop Chrome'], channel: "chrome" },
+      use: { ...devices["Desktop Chrome"], channel: "chrome" },
     },
     {
-      name: 'firefox',
-      use: { ...devices['Desktop Firefox'] },
+      name: "firefox",
+      use: { ...devices["Desktop Firefox"] },
     },
     {
-      name: 'webkit',
-      use: { ...devices['Desktop Safari'] },
+      name: "webkit",
+      use: { ...devices["Desktop Safari"] },
     },
   ],
   webServer: [