test(perf): gate long-session browser and active reconnect workflows

.github/workflows/ci.yml

@@ -206,6 +206,9 @@ jobs:
       - name: Install (immutable)
         run: pnpm install --frozen-lockfile
 
+      - name: Install benchmark browser
+        run: pnpm --filter @deepseek-ai/dsh-benchmarks exec playwright install --with-deps chromium
+
       - name: Run performance benchmarks
         env:
           DSH_GATE_VERBOSE: '1'