Add support for local images/icons in components and CSS

[nateKlaux]

Relative paths to locally hosted images/icons don't resolve in components (e.g., <Card>) or CSS. Only absolute URLs work. Support for relative paths would simplify asset management.

Examples:

<Card 
    title="Title" 
    icon={<img src="./assets/icon.svg" alt="icon"/>} 
    href="/path/"
/>

img.logo {
    content: url("./images/logo.png");
}