Add support for "content.svelte" content scripts

Feature Request

In Svelte 5 it's possible to use "svelte.{js,ts}" extension files to use svelte runes inside, however when trying this in WXT as "test.content.svelte.{js,ts}" it outputs the correct file, but content script not runs in the browser and producing "Unchecked runtime.lastError: The message port closed before a response was received." error

This would be useful in case Svelte props should be amended at runtime. As in my case when I am kinda trying to catch Adobe Analytics analytics request and display it on the page

Is your feature request related to a bug?

N/A

What are the alternatives?

To use legacy Svelte API, but they will be removed in the future

Additional context

https://svelte.dev/docs/svelte/svelte-js-files

Unchecked runtime.lastError: The message port closed before a response was received.
generic-67DrFc4U.mjs:32 Uncaught (in promise) Error: No response

Start by tracing how WXT processes test.content.svelte.{js,ts} content-script entry points and compare that path with regular content scripts. Reproduce the browser failure, then verify that a Svelte 5 content script runs successfully without the message-port error.