feat: Allow `dependsOn` to pass default add-on options if the user doesn't specify them

While authoring the sv community add-on for shadcn-svelte, I found myself wishing to pass predefined default options to add-on dependencies.

For example, rather than just defining an add-on dependency like this:

	// ...
	setup: ({ dependsOn }) => {
		dependsOn("tailwindcss");
	},

we could have something that allows default options:

	// ...
	setup: ({ dependsOn }) => {
		dependsOn("tailwindcss", { plugins: [] });
	},

so if the users calls the add-on without adding the dependency like so:

sv add @shadcn-svelte

then the interactive prompt won't appear for them for tailwindcss.

Of course, if they do specify the dependency:

sv add @shadcn-svelte tailwindcss

then the prompt for tailwindcss's options will appear like normal. Likewise, if the add-on just does dependsOn("tailwindcss"), then the prompt for options will also appear.

Start by tracing how the sv add command handles dependsOn dependencies, explicit dependency arguments, and interactive option prompts. Compare the three examples in the issue: default options should suppress the prompt only when the dependency is omitted, while explicitly requested dependencies or dependencies without defaults should prompt normally.