fix(e2e): cross-protocol browser.execute() — works with both WebDriver + CDP

Root cause: WebDriverIO devtools protocol wraps functions in a polyfill
that puts `return` inside eval() (not a function body) → "Illegal return".

Fix: exec() wrapper in helpers/execute.ts converts function args to IIFE
strings before passing to browser.execute(). Works identically on both
WebDriver (Tauri) and CDP/devtools (Electrobun CEF).

- 35 spec files updated (browser.execute → exec)
- 4 config files updated (string-form expressions)
- helpers/actions.ts + assertions.ts updated
- 560 vitest + 116 cargo passing

tests/e2e/wdio.electrobun.conf.js

@@ -113,13 +113,13 @@ export const config = {
   },
 
   async before() {
-    // Wait for Electrobun app to render
+    // Wait for Electrobun app to render — use string script for CDP compatibility
     await browser.waitUntil(
       async () => {
-        const hasEl = await browser.execute(() =>
-          document.querySelector('.app-shell') !== null
-          || document.querySelector('.project-grid') !== null
-          || document.querySelector('.status-bar') !== null
+        const hasEl = await browser.execute(
+          'return document.querySelector(".app-shell") !== null' +
+          ' || document.querySelector(".project-grid") !== null' +
+          ' || document.querySelector(".status-bar") !== null'
         );
         return hasEl;
       },