feat: unified E2E testing engine — 205 tests, dual-stack support

Infrastructure:
- adapters/: base, tauri (port 9750), electrobun (port 9761 + PTY daemon)
- helpers/: 120+ centralized selectors, reusable actions, custom assertions
- wdio.shared.conf.js + stack-specific configs

18 unified specs (205 tests):
splash(6) smoke(15) settings(19) terminal(14) agent(15) search(12)
files(15) comms(10) tasks(10) theme(12) groups(12) keyboard(8)
notifications(10) diagnostics(8) status-bar(12) context(9)
worktree(8) llm-judged(10)

Daemon: --stack tauri|electrobun|both flag
Scripts: test:e2e:tauri, test:e2e:electrobun, test:e2e:both

tests/e2e/adapters/electrobun-adapter.ts

@@ -0,0 +1,139 @@
+/**
+ * Electrobun stack adapter — spawns WebKitWebDriver or electrobun binary,
+ * manages PTY daemon lifecycle for terminal tests.
+ */
+
+import { spawn, type ChildProcess } from 'node:child_process';
+import { createConnection } from 'node:net';
+import { resolve, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { existsSync } from 'node:fs';
+import { StackAdapter, type StackCapabilities } from './base-adapter.ts';
+import type { TestFixture } from '../infra/fixtures.ts';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const PROJECT_ROOT = resolve(__dirname, '../../..');
+const ELECTROBUN_ROOT = resolve(PROJECT_ROOT, 'ui-electrobun');
+
+export class ElectrobunAdapter extends StackAdapter {
+  readonly name = 'electrobun';
+  readonly port = 9761;
+
+  getBinaryPath(): string {
+    return resolve(ELECTROBUN_ROOT, 'build/Agent Orchestrator');
+  }
+
+  getDataDir(fixture: TestFixture): string {
+    return fixture.dataDir;
+  }
+
+  getCapabilities(_fixture: TestFixture): StackCapabilities {
+    return {
+      capabilities: {
+        'wdio:enforceWebDriverClassic': true,
+        browserName: 'webkit',
+      },
+    };
+  }
+
+  setupDriver(): Promise<ChildProcess> {
+    return new Promise((res, reject) => {
+      // Check port is free
+      const preCheck = createConnection({ port: this.port, host: 'localhost' }, () => {
+        preCheck.destroy();
+        reject(new Error(
+          `Port ${this.port} already in use. Kill: lsof -ti:${this.port} | xargs kill`
+        ));
+      });
+
+      preCheck.on('error', () => {
+        preCheck.destroy();
+
+        // Try WebKitWebDriver first (system-installed), fall back to electrobun binary
+        const driverBin = this.findWebDriver();
+        const driver = spawn(driverBin, ['--port', String(this.port)], {
+          stdio: ['ignore', 'pipe', 'pipe'],
+          env: {
+            ...process.env,
+            AGOR_TEST: '1',
+          },
+        });
+
+        driver.on('error', (err) => {
+          reject(new Error(
+            `Failed to start WebDriver for Electrobun: ${err.message}. ` +
+            'Ensure WebKitWebDriver or the Electrobun binary is available.'
+          ));
+        });
+
+        // TCP readiness probe
+        const deadline = Date.now() + 15_000;
+        const probe = () => {
+          if (Date.now() > deadline) {
+            reject(new Error(`WebDriver not ready on port ${this.port} within 15s`));
+            return;
+          }
+          const sock = createConnection({ port: this.port, host: 'localhost' }, () => {
+            sock.destroy();
+            res(driver);
+          });
+          sock.on('error', () => {
+            sock.destroy();
+            setTimeout(probe, 300);
+          });
+        };
+        setTimeout(probe, 500);
+      });
+    });
+  }
+
+  teardownDriver(driver: ChildProcess): void {
+    driver.kill();
+  }
+
+  async startPtyDaemon(): Promise<ChildProcess> {
+    const daemonPath = resolve(ELECTROBUN_ROOT, 'src/pty-daemon/agor-ptyd');
+    const altPath = resolve(PROJECT_ROOT, 'target/debug/agor-ptyd');
+    const bin = existsSync(daemonPath) ? daemonPath : altPath;
+
+    if (!existsSync(bin)) {
+      throw new Error(`PTY daemon binary not found at ${daemonPath} or ${altPath}`);
+    }
+
+    const daemon = spawn(bin, [], {
+      stdio: ['ignore', 'pipe', 'pipe'],
+      env: { ...process.env, AGOR_TEST: '1' },
+    });
+
+    // Wait for daemon to be ready (simple delay — daemon binds quickly)
+    await new Promise((r) => setTimeout(r, 1000));
+    return daemon;
+  }
+
+  stopPtyDaemon(daemon: ChildProcess): void {
+    daemon.kill('SIGTERM');
+  }
+
+  verifyBinary(): void {
+    if (!existsSync(this.getBinaryPath())) {
+      throw new Error(
+        `Electrobun binary not found at ${this.getBinaryPath()}. ` +
+        'Build with: cd ui-electrobun && bun run build:canary'
+      );
+    }
+  }
+
+  private findWebDriver(): string {
+    // Check common WebKitWebDriver locations
+    const candidates = [
+      '/usr/bin/WebKitWebDriver',
+      '/usr/local/bin/WebKitWebDriver',
+      resolve(ELECTROBUN_ROOT, 'node_modules/.bin/webkitwebdriver'),
+    ];
+    for (const c of candidates) {
+      if (existsSync(c)) return c;
+    }
+    // Fall back to PATH resolution
+    return 'WebKitWebDriver';
+  }
+}