Fix review P2s: lockfile, model path convention, trap robustness

- Regenerate uv.lock after adding fastapi/uvicorn deps so uv sync
  --locked no longer fails
- B3 scripts: default MODEL to $HOME/models/... matching documented
  convention and other launch scripts (repo has no models/ directory)
- launch_elastic_p2p: append || true to each trap command so set -e
  doesn't abort cleanup when jobs -p is empty and EngineCore orphans
  remain

scripts/launch_elastic_p2p.sh

@@ -27,7 +27,7 @@ PROXY_PORT=9090
 HEAVY_THRESHOLD="${HEAVY_THRESHOLD:-20000}"
 MAX_OFFLOAD="${MAX_OFFLOAD:-4}"
 
-trap 'echo "Cleaning up..."; kill $(jobs -p) 2>/dev/null; pkill -9 -f "vllm serve" 2>/dev/null; pkill -9 -f "EngineCore" 2>/dev/null; pkill -9 -f cache_aware_proxy 2>/dev/null; wait 2>/dev/null' EXIT INT TERM
+trap 'echo "Cleaning up..."; kill $(jobs -p) 2>/dev/null || true; pkill -9 -f "vllm serve" 2>/dev/null || true; pkill -9 -f "EngineCore" 2>/dev/null || true; pkill -9 -f cache_aware_proxy 2>/dev/null || true; wait 2>/dev/null || true' EXIT INT TERM
 
 echo "=== Elastic P2P Offload (${N_INSTANCES}× TP=1 kv_both) ==="
 echo "  Model:           $MODEL"