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/tauri-adapter.ts

@@ -0,0 +1,96 @@
+/**
+ * Tauri stack adapter — spawns tauri-driver, TCP readiness probe,
+ * routes through tauri:options capabilities.
+ */
+
+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, '../../..');
+
+export class TauriAdapter extends StackAdapter {
+  readonly name = 'tauri';
+  readonly port = 9750;
+
+  getBinaryPath(): string {
+    return resolve(PROJECT_ROOT, 'target/debug/agent-orchestrator');
+  }
+
+  getDataDir(fixture: TestFixture): string {
+    return fixture.dataDir;
+  }
+
+  getCapabilities(fixture: TestFixture): StackCapabilities {
+    return {
+      capabilities: {
+        'wdio:enforceWebDriverClassic': true,
+        'tauri:options': {
+          application: this.getBinaryPath(),
+          env: fixture.env,
+        },
+      },
+    };
+  }
+
+  setupDriver(): Promise<ChildProcess> {
+    return new Promise((res, reject) => {
+      // Check port is free first
+      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();
+        const driver = spawn('tauri-driver', ['--port', String(this.port)], {
+          stdio: ['ignore', 'pipe', 'pipe'],
+        });
+
+        driver.on('error', (err) => {
+          reject(new Error(
+            `Failed to start tauri-driver: ${err.message}. Install: cargo install tauri-driver`
+          ));
+        });
+
+        // TCP readiness probe
+        const deadline = Date.now() + 10_000;
+        const probe = () => {
+          if (Date.now() > deadline) {
+            reject(new Error(`tauri-driver not ready on port ${this.port} within 10s`));
+            return;
+          }
+          const sock = createConnection({ port: this.port, host: 'localhost' }, () => {
+            sock.destroy();
+            res(driver);
+          });
+          sock.on('error', () => {
+            sock.destroy();
+            setTimeout(probe, 200);
+          });
+        };
+        setTimeout(probe, 300);
+      });
+    });
+  }
+
+  teardownDriver(driver: ChildProcess): void {
+    driver.kill();
+  }
+
+  verifyBinary(): void {
+    if (!existsSync(this.getBinaryPath())) {
+      throw new Error(
+        `Tauri binary not found at ${this.getBinaryPath()}. ` +
+        'Build with: npm run tauri build --debug --no-bundle'
+      );
+    }
+  }
+}