feat: add fetchpriority JSX attribute to img, link, script, and iframe

[Burzmalian]

Prerequisites

• I have read the Contributing Guidelines.
• I agree to follow the Code of Conduct.
• I have searched for existing issues that already include this feature request, without success.

Describe the Feature Request

Add the standardized fetchpriority / fetchPriority attribute (values: 'high' | 'low' | 'auto') to the JSX type declarations for <img>, <link>, <script>, and <iframe> elements in stencil-public-runtime.ts.

Describe the Use Case

Developers using Stencil components that render these elements need type-safe access to fetchpriority to hint resource loading priority to the browser — e.g. marking above-the-fold hero images as fetchpriority="high" or deferring non-critical scripts as fetchpriority="low". Without the type declaration, TypeScript flags this as an error.

Describe Preferred Solution

Add both the camelCase (fetchPriority) and lowercase (fetchpriority) variants to JSXBase.IframeHTMLAttributes, JSXBase.ImgHTMLAttributes, JSXBase.LinkHTMLAttributes, and JSXBase.ScriptHTMLAttributes, following the same dual-property convention already used for crossOrigin/crossorigin, srcSet/srcset, etc.

Describe Alternatives

Consumers can currently work around this by casting to any or using // @ts-ignore, which is undesirable.

Related Code

// currently causes a TypeScript error:
<img src="hero.webp" fetchpriority="high" />

// after this change, typed correctly:
<img src="hero.webp" fetchPriority="high" />

Additional Information

• MDN reference: https://developer.mozilla.org/en-US/docs/Web/API/HTMLImageElement/fetchPriority
• fetchpriority is now broadly supported across Chrome, Edge, Firefox, and Safari.
• The older non-standard importance attribute already present in these interfaces is a predecessor; fetchpriority is the standardized replacement but importance is intentionally left for backward compatibility.

[johnjenkins]

thanks @Burzmalian for the contribution 🙏