Playground: sync visualization tests and reference images from Babylon.js (#1684)

Sync visualization tests + reference images from Babylon.js, plus a
test-runner fix.

Test config (Apps/Playground/Scripts/config.json)

- Imports the full visualization test list from Babylon.js: 720 tests
total (was 94).
- 96 active, 624 disabled with explicit disabledReason. Three reason
categories:
    * Pixel comparison fails on Babylon Native
    * Test crashes / hangs on Babylon Native
* Requires WebGL2-only feature (was excludedEngines:["webgl2"] upstream)
- Drops upstream's excludedEngines field (Babylon Native uses
excludeFromAutomaticTesting).
- Tests blocked only by excludedEngines:["webgl1"] upstream are now
active here.
- Stripped errorRatio from disabled tests (no effect when test doesn't
run).

Reference images (Apps/Playground/ReferenceImages/)

- Mirrors
Babylon.js/packages/tools/tests/test/visualization/ReferenceImages/,
excluding WebGPU.
- Re-saved as RGBA PNG with alpha channel (Babylon Native pipeline
expects RGBA).

Test-runner fix (Apps/Playground/Scripts/validation_native.js)

- recursiveRunTest was genuinely recursive — each iteration added 3
stack frames.
- At ~91 tests, Chakra threw Out of stack space, killing Win32_x64_D3D11
and Win32_x64_D3D11_Sanitizers.
- Fix: defer the next iteration via setTimeout(() =>
recursiveRunTest(i), 0) so each test runs on a fresh stack.
- setTimeout was already used elsewhere in the file (line 167), so no
new dependency.

CI status

All 28 checks green on c512e77 (V8/JSI/Chakra D3D11, D3D12, Sanitizers,
Linux JSC, Android, iOS, UWP, macOS, installations).

Follow-up (out of scope)

The 624 disabled tests carry actionable disabledReason strings so a
follow-up PR can re-enable them as the underlying engine issues are
fixed.

---------

Co-authored-by: Branimir Karadzic <branimirkaradzic@gmail.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people