fix(stacks-svelte): pre-bundle dayjs plugins with .js extension to fix CI test flake (#2224)

* fix(stacks-svelte): pre-bundle dayjs plugins with .js extension in optimizeDeps

stacks-utils imports dayjs/plugin/relativeTime.js and updateLocale.js
with explicit .js extensions. Vite's optimizeDeps.include entries without
.js don't match these, so Vite discovers them as new deps mid-test run,
triggers re-optimization + reload, and kills in-flight test module fetches
(manifesting as a Navigation test import failure in CI).

CI always has a cold Vite cache; locally the .js variants get cached on the
first run, masking the issue.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore: trigger CI tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* changeset: patch for stacks-svelte dayjs optimizeDeps fix

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: dancormier

.changeset/swift-clocks-ring.md

@@ -0,0 +1,5 @@
+---
+"@stackoverflow/stacks-svelte": patch
+---
+
+Pre-bundle dayjs plugins with .js extension in optimizeDeps

packages/stacks-svelte/vite.config.ts

@@ -21,7 +21,9 @@ export default defineConfig({
             "@stackoverflow/stacks-icons-legacy/icons",
             "dayjs",
             "dayjs/plugin/relativeTime",
+            "dayjs/plugin/relativeTime.js",
             "dayjs/plugin/updateLocale",
+            "dayjs/plugin/updateLocale.js",
             // svelte-sonner must be pre-bundled to ensure its virtual CSS modules
             // (from <style global> blocks) are properly resolved during test execution.
             // Without pre-bundling, CI environments may trigger mid-test re-optimization,