fix: exclude e2e-docker tests from Vitest runner

The Playwright-based Docker e2e tests use test.describe() which is
incompatible with Vitest. Exclude tests/e2e-docker/ from Vitest's
test discovery, matching the existing tests/e2e/ exclusion.

vitest.config.ts

@@ -24,6 +24,7 @@ export default defineConfig({
     },
     exclude: [
       "tests/e2e/**",
+      "tests/e2e-docker/**",
       "**/node_modules/**",
       "**/dist/**",
       "**/.{idea,git,cache,output,temp}/**",