Add Mono-compat loader shims to browserhost (withRuntimeOptions + legacy default export)

[pavelsavara]

Restores backward compatibility with the Mono loader's DotnetHostBuilder / legacy entrypoint surface in the CoreCLR browserhost loader, without adding any of it to the announced public TypeScript definitions.

Changes

loader/host-builder.ts

• Adds an internal withRuntimeOptions(runtimeOptions: string[]) method to HostBuilder, mirroring the Mono loader's method. It validates the argument is a string array and merges the options into the loader config.
• Marked // internal and intentionally not added to the public DotnetHostBuilder type, so it stays off the announced API surface.

loader/dotnet.ts

• Adds a legacy default export (export default legacyExport) matching the Mono loader's createDotnetRuntime / createEmscripten signature: it accepts a DotnetModuleConfig object or a (api) => DotnetModuleConfig factory, applies config via withConfig, assigns the module config onto Module, and returns dotnet.create(). This lets existing Mono-style consumers that import createDotnetRuntime from './dotnet.js' keep working.
• Tightens the dotnet export type from DotnetHostBuilder | undefined to DotnetHostBuilder.

Validation

• npm run rollup:debug compiles cleanly.

Note

This PR description was generated with AI assistance.

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[Copilot]

🟡 Changes recommended

Merge DotnetModuleConfig.config into the loader configuration before creating the runtime.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Adds browserhost compatibility with Mono’s runtime-options API and legacy runtime entrypoint.

Changes:

• Adds internal withRuntimeOptions.
• Restores legacy runtime creation/export handling.

File summaries

File	Summary
src/native/libs/Common/JavaScript/loader/host-builder.ts	Adds runtime-options configuration support.
src/native/libs/Common/JavaScript/loader/dotnet.ts	Adds legacy runtime creation support; config is not merged into loader configuration, so caller-supplied settings are ignored.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

🟢 Approval recommended

The reviewed compatibility changes are complete with no unresolved blocking issues.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0 new
• Review effort level: Lite