Add CanvasRenderingContext2D.isPointInStroke

[GtechGovind]

Fixes #1770.

I added CanvasRenderingContext2D.isPointInStroke() using Cairo's native stroke hit testing.

• Expose the method through the native binding and TypeScript declarations.
• Convert canvas-space hit-test coordinates into Cairo's current user space so transformed paths behave like the browser API.
• Normalize ellipse angles before creating the Cairo arc, which makes the bundled full-circle, scaled-dash WPT exercise the new API correctly.
• Add behavioral coverage for hits, misses, invalid arguments, and transformed paths, plus a type-definition regression test and changelog entries.

Validation on macOS Apple Silicon with Node 26.0.0 and Zig 0.16.0:

• zig build -j4: passed.

• Focused Context2d#isPointInStroke() unit test: passed.

• Bundled 2d.path.isPointInStroke.scaleddashes WPT: passed.

• npm test -- --reporter dot: 306 passed, six pending.

• npm run lint and npm run tsd: passed.

• The complete generated WPT corpus is not currently green: 338 passed, nine pending, and 118 failures across unrelated unsupported APIs and harness gaps.

• Have you updated CHANGELOG.md?