feat(render-method-2024)!: align RenderTemplate2024 with downstream renderer

[ashleythedeveloper]

This PR aligns the RenderTemplate2024 interface and provider with the shape already produced and consumed by the downstream vckit renderer (packages/renderer/src/providers/render-template-2024.ts), so render methods built via constructRenderMethod round-trip cleanly through the renderer with no missing fields.

The renderer reads name, mediaType, and digestMultibase, and a type array containing "RenderTemplate2024". The previous interface only modelled mediaQuery, template, and url, and emitted unset optional fields as empty strings, neither of which match what the renderer expects.

Closes #18

Breaking changes

• RenderTemplate2024.type is now string[] rather than the literal RenderMethodType.RenderTemplate2024. Direct consumers of the type (anyone reading renderMethod.type === 'RenderTemplate2024') must update to renderMethod.type.includes('RenderTemplate2024').
• RenderMethod2024.construct no longer emits unset optional fields. Code that relies on mediaQuery: '' or url: '' always being present must check for the property before reading it.

Additions

• New optional fields on RenderTemplate2024: name, mediaType, digestMultibase. All are accepted via the extra argument of constructRenderMethod and only emitted when supplied as non-empty strings.
• extractRenderTemplate resolves the discriminator from either string or string[] type values, throwing UnsupportedRenderMethodError (with diagnostic detail for empty or unsupported arrays) when no supported entry is present.

Out of scope (potential follow-ups)

• Tightening type to a tuple form ([RenderMethodType.RenderTemplate2024, ...string[]]) to encode the "must contain" invariant in the type system.
• Splitting RenderTemplate2024 into Input vs Emitted variants to express the producer/consumer asymmetry.
• Validating the discriminator inside constructRenderMethod (currently only the extract path validates).

Test plan

• type is emitted as an array containing "RenderTemplate2024"
• name, mediaType, and digestMultibase are accepted via extra and round-tripped onto the constructed render method
• Optional fields supplied as undefined, missing, empty string, or non-string values are omitted from the constructed render method (no empty-string emission)
• template is omitted when empty (URL-only construction)
• extractRenderTemplate resolves the render method type from a string[] discriminator, including arrays with additional entries
• extractRenderTemplate passes through a non-array type unchanged for WebRenderingTemplate2022
• extractRenderTemplate throws UnsupportedRenderMethodError with the joined unsupported entries, and with <empty> when the array is empty
• yarn build, yarn test, yarn lint, and yarn format all pass

[github-actions]

Code Coverage Report

Lines	Statements	Branches	Functions
	100% (145/145)	97.22% (35/36)	100% (26/26)

Tests	Skipped	Failures	Errors	Time
73	0 💤	0 ❌	0 🔥	1.954s ⏱️