chore(studio): point plugin test at fai_plugins/ instead of fai_modules/

Studio plugins moved to a dedicated fai_plugins/ workspace
directory; integration test path updated to match.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

test/integration/plugin_theme_test.dart

@@ -12,7 +12,7 @@
 // Pre-reqs (handled by HubFixture's skip-when-missing path):
 //   - fai binary on PATH or at ../fai_platform/target/release/fai
 //   - studio-theme-solarized plugin built to module.wasm in its
-//     fai_modules dir.
+//     fai_plugins dir.
 
 import 'dart:io';
 
@@ -33,7 +33,7 @@ void main() {
         // add network + bundle-fetch latency that doesn't
         // belong in an in-process round-trip test.
         final pluginSrc = Directory(
-          '../fai_modules/studio-theme-solarized',
+          '../fai_plugins/studio-theme-solarized',
         );
         if (!await pluginSrc.exists()) {
           markTestSkipped('studio-theme-solarized source not available');