Modernize client to v2: resource-oriented, typed, full API coverage

Rewrite the TestingBot PHP client (PHP 8.1+) around a resource-grouped
`TestingBot\Client` with a backward-compatible `TestingBot\TestingBotAPI`
facade. The 1.x flat method names/signatures are preserved; the one behaviour
change is that failures now throw typed exceptions instead of returning an
`['error' => ...]` array.

Highlights:
- Full API coverage across 13 resources (tests, builds, storage, tunnels, user,
  team-management, codeless lab tests + suites, screenshots, devices, browsers,
  configuration, jobs).
- Single cURL chokepoint behind HttpClientInterface (timeouts, TLS verify,
  versioned UA, curl_errno -> NetworkException, HTTP-status checking) with a
  mockable seam for tests.
- Typed exception hierarchy (Authentication/NotFound/RateLimit/Api/Network).
- Replace PHP8-fatal mime_content_type() with ext-fileinfo.
- PSR-4 autoload; drop bogus runtime deps (phpunit-selenium, paratest, appium);
  type=library; add phpstan (L8), php-cs-fixer (PSR-12), .editorconfig.
- 86 unit tests via FakeHttpClient (no network) + gated live integration suite.
- GitHub Actions: CI matrix PHP 8.1-8.4 + token-free tag-driven release workflow.
- Rewritten README, CHANGELOG, CLAUDE.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

remove travis badge

Add TestingBot Storage calls

phpunit

update README