fix: use SSR format compatible with nginx SSI for props.id (#16820)

* fix: use SSR format compatible with nginx SSI for props.id

* changeset

---------

Co-authored-by: Rich Harris <hello@rich-harris.dev>

.changeset/silly-schools-divide.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: use nginx SSI-compatible comments for `$props.id()`

packages/svelte/src/internal/client/dom/template.js

@@ -365,7 +365,7 @@ export function props_id() {
 		hydrating &&
 		hydrate_node &&
 		hydrate_node.nodeType === COMMENT_NODE &&
-		hydrate_node.textContent?.startsWith(`#`)
+		hydrate_node.textContent?.startsWith(`$`)
 	) {
 		const id = hydrate_node.textContent.substring(1);
 		hydrate_next();

packages/svelte/src/internal/server/index.js

@@ -448,7 +448,7 @@ export function once(get_value) {
  */
 export function props_id(renderer) {
 	const uid = renderer.global.uid();
-	renderer.push('<!--#' + uid + '-->');
+	renderer.push('<!--$' + uid + '-->');
 	return uid;
 }