Simplify interop once the upstreamed html-to-image fixes ship in a vendored release

[Kebechet]

Version 1.11.13.1 added two interop-level WebKit mitigations (stabilised captures, bounded capture time) plus a pre-existing toBlob deviation. All three are now proposed upstream. When a PR below is merged and a vendored release containing it ships, the matching wrapper code can be simplified.

Each item requires vendoring the new upstream release first (update the provenance table + SHA-256 in the README).

• fix: resolve createImage when decode() rejects instead of hanging forever bubkoo/html-to-image#589 (createImage never settles when decode() rejects) — keep CaptureTimeoutMs and withCaptureTimeout as a plain safety bound, but drop the "upstream has no rejection path" rationale from their docs (html-to-image-interop.js, HtmlToImageOptions.CaptureTimeoutMs remarks, README iOS section).
• fix: forward type and quality options from toBlob to canvasToBlob bubkoo/html-to-image#590 (toBlob drops type/quality) — replace the manual canvas-to-blob step in toStream with upstream toBlob (still through captureStable), and retire the "One deliberate deviation from upstream" README section. Keep Capture_JpegStory_ReturnsBytesWithAJpegSignature as the regression gate.
• feat: add stabilizationAttempts option for blank large images in WebKit captures bubkoo/html-to-image#591 (opt-in stabilizationAttempts) — remove the interop captureStable loop and forward StabilizeAttempts to upstream's stabilizationAttempts instead. Public option surface stays unchanged; re-run the iOS device harness (tools/ios-device-harness) to confirm the upstream implementation still produces 0 blanks on a real iPhone before deleting the local loop.

The exact code seams are marked with "Upstreamed as ..." comments in wwwroot/html-to-image-interop.js, HtmlToImageOptions.cs, and the README.