server: support GptOss in TP engine + benchmark script

- tp_engine.rs: TpModel enum dispatches between Qwen3 and GptOss based on
  config.is_moe(). Server auto-detects model type on startup.
- tools/run_gpt_oss_bench.sh: one-click benchmark comparing xserv (TP=2)
  vs llama.cpp (BF16 GGUF) on GSM8K quality + speed

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tools/run_gpt_oss_bench.sh

@@ -0,0 +1,76 @@
+#!/bin/bash
+set -e
+cd /opt/wjh/projects/xserv
+
+# Kill any existing servers
+pkill -f 'xserv-server.*18080' 2>/dev/null || true
+pkill -f 'llama-server.*18090' 2>/dev/null || true
+sleep 2
+
+QUALITY_LIMIT="${1:-200}"
+echo "=== gpt-oss-20b Benchmark: xserv (TP=2) vs llama.cpp (BF16) ==="
+echo "GSM8K limit: $QUALITY_LIMIT problems"
+
+# Start llama.cpp (GPU 2,3)
+echo 'Starting llama-server on GPU 2,3...'
+CUDA_VISIBLE_DEVICES=2,3 nohup third_party/llama.cpp/build/bin/llama-server \
+    -m /opt/wjh/models/gpt-oss-20b-gguf/gpt-oss-20b-bf16.gguf \
+    --port 18090 -ngl 999 -c 4096 \
+    > /tmp/llama-gptoss.log 2>&1 &
+
+# Start xserv (GPU 0,1, TP=2)
+echo 'Starting xserv-server on GPU 0,1 (TP=2)...'
+CUDA_VISIBLE_DEVICES=0,1 nohup ./target/release/xserv-server \
+    /opt/wjh/models/gpt-oss-20b-bf16 \
+    --port 18080 --tp 2 --max-batch 1 --max-seq-len 4096 \
+    > /tmp/xserv-gptoss.log 2>&1 &
+
+# Wait for both to be ready
+echo 'Waiting for servers to start...'
+for i in $(seq 1 60); do
+    sleep 2
+    XOK=$(curl -s http://localhost:18080/health 2>/dev/null || echo '')
+    LOK=$(curl -s http://localhost:18090/health 2>/dev/null || echo '')
+    if [ -n "$XOK" ] && [ -n "$LOK" ]; then
+        echo "Both servers ready! (${i}x2s)"
+        break
+    fi
+    if [ $i -eq 60 ]; then
+        echo 'ERROR: Timeout waiting for servers'
+        echo '--- xserv log ---'
+        tail -10 /tmp/xserv-gptoss.log
+        echo '--- llama log ---'
+        tail -10 /tmp/llama-gptoss.log
+        exit 1
+    fi
+done
+
+echo ''
+echo '=== Running GSM8K quality benchmark ==='
+python3 -m tools.bench.runner \
+    --xserv-base-url http://localhost:18080 \
+    --xserv-model-id gpt-oss-20b \
+    --llama-base-url http://localhost:18090 \
+    --suite quality \
+    --quality-limit "$QUALITY_LIMIT" \
+    --max-seq-len 4096 2>&1 | tee /tmp/bench_gptoss_quality.log
+
+echo ''
+echo '=== Running speed benchmark ==='
+python3 -m tools.bench.runner \
+    --xserv-base-url http://localhost:18080 \
+    --xserv-model-id gpt-oss-20b \
+    --llama-base-url http://localhost:18090 \
+    --suite speed \
+    --max-seq-len 4096 2>&1 | tee /tmp/bench_gptoss_speed.log
+
+# Cleanup
+echo ''
+echo '=== Cleaning up ==='
+pkill -f 'xserv-server.*18080' 2>/dev/null || true
+pkill -f 'llama-server.*18090' 2>/dev/null || true
+
+echo ''
+echo '=== BENCHMARK COMPLETE ==='
+echo "Quality results: /tmp/bench_gptoss_quality.log"
+echo "Speed results: /tmp/bench_gptoss_speed.log"