fix: ensure derived reactions have their version kept in sync with the reactive graph

.changeset/rich-turtles-learn.md

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+---
+'svelte': patch
+---
+
+fix: ensure derived reactions have their version kept in sync with the reactive graph

packages/svelte/tests/runtime-runes/samples/derived-version-sync/_config.js

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+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target, logs }) {
+		let [btn1] = target.querySelectorAll('button');
+
+		btn1?.click();
+		flushSync();
+
+		btn1?.click();
+		flushSync();
+
+		logs.length = 0;
+
+		btn1?.click();
+		flushSync();
+
+		assert.deepEqual(logs, ['a', { value: 1 }]);
+
+		logs.length = 0;
+
+		btn1?.click();
+		flushSync();
+
+		assert.deepEqual(logs, ['a', { value: 2 }, 'b', { a: 2 }, 'c', { b: 2 }]);
+	}
+});

packages/svelte/tests/runtime-runes/samples/derived-version-sync/main.svelte

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+<script>
+	let trigger = $state(false)
+	let index = 0;
+
+	let a = $derived.by(() => {
+		trigger;
+		const value = [1,2,1][index++%3];
+		console.log("a", { value });
+		return value
+	})
+
+	let b = $derived.by(() => {
+		console.log("b", { a });
+		return a;
+	});
+
+	let c = $derived.by(() => {
+		console.log("c", { b });
+		return undefined;
+	});
+
+	$effect(() => {
+		c;
+		console.log('effect')
+	});
+</script>
+
+<button onclick={() => trigger = !trigger}>invalidate</button>