Fix review bugs: PD-sep counter leaks, hardcoded paths, missing deps

Critical:
- cache_aware_proxy: _handle_pd_sep leaked p_inst.num_requests (never
  decremented) and never managed d_inst.num_requests; fix media_type
  from application/json to text/event-stream for SSE stream

High:
- b3_sweep/b3_isolated_policy/b3_analyze: replace hardcoded
  /home/admin/cpfs/wjh/ ROOT with script-relative $(dirname "$0")/..
- b3_analyze: replace hardcoded 8-port WORKER_MAP with dynamic
  generation from BASE_PORT and N_INSTANCES

Medium:
- analyze_breakdown: warn on stderr when records are skipped (was silent)
- deploy_vllm_patches: fail-fast on SSH/SCP errors instead of
  continuing with empty VENV_SITE
- pyproject.toml: declare fastapi and uvicorn as runtime dependencies
- launch_elastic_p2p: kill EngineCore and proxy in trap handler to
  prevent GPU memory leaks on exit

scripts/cache_aware_proxy.py

@@ -1176,6 +1176,7 @@ async def _handle_pd_sep(api, req_data, request_id, token_ids, input_length,
     p_headers = {**headers, "X-data-parallel-rank": "0"}
 
     p_inst.ongoing_tokens += input_length
+    p_inst.num_requests += 1
     breakdown["t_prefill_sent"] = _time.monotonic()
     breakdown["t_prefill_sent_unix"] = _time.time()
 
@@ -1194,9 +1195,11 @@ async def _handle_pd_sep(api, req_data, request_id, token_ids, input_length,
         raise HTTPException(status_code=502, detail=f"Prefill failed: {e}")
     finally:
         p_inst.ongoing_tokens -= input_length
+        p_inst.num_requests -= 1
 
     # Send decode
     d_inst.ongoing_tokens += input_length
+    d_inst.num_requests += 1
     parsed = urllib.parse.urlparse(str(p_inst.client.base_url))
     bootstrap_addr = f"http://{parsed.hostname}:{p_inst.bootstrap_port}"
 
@@ -1232,9 +1235,10 @@ async def _handle_pd_sep(api, req_data, request_id, token_ids, input_length,
             breakdown["t_done"] = _time.monotonic()
             breakdown["t_done_unix"] = _time.time()
             d_inst.ongoing_tokens -= input_length
+            d_inst.num_requests -= 1
             _breakdown_log.append(breakdown)
 
-    return StreamingResponse(generate(), media_type="application/json")
+    return StreamingResponse(generate(), media_type="text/event-stream")
 
 
 @app.get("/breakdown")