Allow csp configuration to dynamically read env variables

Describe the problem

I have an "adapter-node" app deployed somewhere, I have different environments (dev, qa, prod) and i would like to provide different values to the csp configuration based on the env variables set in each environment at runtime.

Describe the proposed solution

Maybe sveltekit may support "app.html" like syntax to read the env variables at runtime:

csp: {
	directives: {
		'frame-src': ['self', '%sveltekit.env.APP_PUBLIC_TRUSTED_DOMAIN%']
	}
}

Alternatives considered

No response

Importance

would make my life easier

Additional Information

No response

Start by tracing adapter-node's CSP configuration and the app.html environment-variable handling. Determine how runtime values should be supplied for each deployment environment, and define tests showing that CSP directives receive those values without requiring a rebuild.