fix: Element Call assets land flat in public/element-call (fixes desktop calls)

vite-plugin-static-copy v4 preserves the full source path under dest, so the
old { src: '.../dist', dest: 'public', rename: 'element-call' } target placed
Element Call at dist/public/node_modules/@element-hq/element-call-embedded/dist/
instead of dist/public/element-call/. The call widget URL
(/public/element-call/index.html) therefore 404'd.

This broke voice/video calls on cinny-desktop (served via tauri-plugin-localhost
from a fresh build). The web client only kept working because its deployed
/public/element-call/ was a stale artifact from before the v4 bump — the next
web rebuild would have broken calls there too.

Fix: copy the dist directory to public/element-call with rename:{stripBase:4}
to strip the source path segments, mirroring the android/locales targets.
Verified: a fresh build now produces dist/public/element-call/index.html +
assets/ with intact relative asset refs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

vite.config.js

@@ -13,9 +13,19 @@ import buildConfig from './build.config';
 const copyFiles = {
   targets: [
     {
+      // Element Call's dist must land flat in public/element-call/ so the call
+      // widget URL (/public/element-call/index.html) resolves. v4.x of
+      // vite-plugin-static-copy preserves the full source path under dest, so
+      // we strip the 4 leading segments of the source base
+      // (node_modules/@element-hq/element-call-embedded/dist) — mirroring the
+      // stripBase pattern used by the android/locales targets below. The old
+      // `rename: 'element-call'` form silently produced
+      // public/node_modules/.../dist/ under v4.x, 404ing the widget (calls
+      // broke on cinny-desktop; web only worked because its deployed copy was
+      // a stale artifact from before the vite-plugin-static-copy v4 bump).
       src: 'node_modules/@element-hq/element-call-embedded/dist',
-      dest: 'public',
-      rename: 'element-call',
+      dest: 'public/element-call',
+      rename: { stripBase: 4 },
     },
     {
       src: 'config.json',