feat: add waitForElement, assertions, batch commands, WebView inspection, async ADB, error classification, iOS fixes (v2.11.0)

New tools:
- wait_for_element: poll UI hierarchy until element found or timeout
- assert_visible / assert_not_exists: instant UI verification without screenshots
- batch_commands: execute multiple commands in single MCP round-trip
- get_webview: inspect WebView content via Chrome DevTools Protocol (Android)

Bug fixes:
- iOS longPress now uses WDA Actions API (pointerDown+pause+pointerUp) instead of tap
- iOS swipeDirection uses dynamic screen center from WDA instead of hardcoded 200x400
- WDA launch mutex prevents parallel xcodebuild launches (race condition)
- Per-platform cachedElements map prevents cross-device element contamination

Improvements:
- Async ADB: execRawAsync, screenshotRawAsync, getUiHierarchyAsync (non-blocking)
- All UI handlers now use async ADB methods
- Typed error classification (DeviceNotFoundError, AdbNotInstalledError, etc.)
- classifyAdbError/classifySimctlError for actionable error messages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>