[Lit] render DSD attributes based on `shadowRootOptions` (#6351)

* [Lit] render DSD attributes based on `shadowRootOptions`

## Changes

- Update `@astrojs/lit`’s `server.js` to properly render elements with `delegatesFocus: false` set in their `shadowRootOptions`.
- Logic is based on `@lit-labs/ssr` [latest implementation as found here](https://github.com/lit/lit/blob/b0c3f82ef0f97326a205e77e7e1043b75a5cc53f/packages/labs/ssr/src/lib/render-value.ts#L738)

## Testing

A test was added to ensure an element with `delegatesFocus` set to true has this attribute properly included in the rendered static markup.

* chore: add changeset

1 files changed, 5 insertions, 1 deletions

diff --git a/packages/integrations/lit/server.js b/packages/integrations/lit/server.js
index da571466f..aa91d1ea8 100644
--- a/packages/integrations/lit/server.js
+++ b/packages/integrations/lit/server.js
@@ -62,7 +62,11 @@ function* render(Component, attrs, slots) {
 	yield `>`;
 	const shadowContents = instance.renderShadow({});
 	if (shadowContents !== undefined) {
-		yield '<template shadowroot="open" shadowrootmode="open">';
+		const { mode = 'open', delegatesFocus } = instance.shadowRootOptions ?? {};
+    // `delegatesFocus` is intentionally allowed to coerce to boolean to
+    // match web platform behavior.
+    const delegatesfocusAttr = delegatesFocus ? ' shadowrootdelegatesfocus' : '';
+		yield `<template shadowroot="${mode}" shadowrootmode="${mode}"${delegatesfocusAttr}>`;
 		yield* shadowContents;
 		yield '</template>';
 	}