[PaulHax]

Context

Bring the published TypeScript declarations into sync with the JavaScript implementation. Downstream projects currently need local declarations for missing modules and corrections for inaccurate signatures.

Results

Declarations cover hundreds more modules and describe their runtime exports, accessors, factory options, and static APIs more accurately. Consumers can remove overlapping local declare module '@kitware/vtk.js/...' shims. Corrected signatures can require call-site updates for nullability, typed arrays, and renderer-specific view APIs.

This PR changes declaration files, their validation configs, and migration documentation. Runtime behavior is unchanged.

Downstream

• VolView: Kitware/VolView#928 removes 310 lines of local @kitware/vtk.js declarations.
• cornerstone3D: vtk-types-compat types custom render-pass locals and removes an invokeEvent suppression.

Changes

• Add missing declarations and correct member signatures, return types, nullability, newInstance options, and static exports.
• Infer typed-array factory results from constructor names, including the Float64Array fallback for optional BigInt constructors.
• Share an ES2020 and DOM baseline across source, ESM, and UMD declaration checks. Consumers using an older TypeScript lib list should add ES2020.BigInt; their target can stay unchanged.
• Match current rendering APIs, including WebGPU storage buffers, texture ownership, mipmaps, multisampling, material properties, and resource release.
• Correct widget event ownership and animation options to match the objects that implement them.
• Type setXFrom and setters without a return value as void, and include null or undefined where accessors can return them.
• Remove named value exports that only exist on a module's default export. Import constants such as DesiredOutputPrecision, VtkDataTypes, BoundaryCondition, and PolygonWithPointIntersectionState from their module's Constants entry point.
• Make vtkPolygon.PolygonIntersectionState a type alias of PolygonWithPointIntersectionState; the old enum values did not match the runtime constants. Use the constants module for runtime values.

PR Checklist

• GitHub Actions CI passed
• Documentation and TypeScript definitions are updated to match these changes

Testing

No runtime tests are added because runtime behavior is unchanged. The companion declaration conformance work covers declaration and consumer contracts separately; runtime fixes remain outside this PR.

Supersedes #3617. This branch lives in Kitware/vtk-js so dependent PRs can target it.

[finetjul]

LGTM