sync: align with enginex-vllm-bi100-qwen36 baseline (1902c81f)

Synced files from EngineX baseline zip (2026-06-30):
- ADD paged_attn.py (root): production paged attention with PyTorch fallback
- ADD launch_service: BI-V100 server startup script with env configuration
- SYNC computility-run.yaml: gpu_memory=0.9, batched_tokens=8192, seq_capture=32768
- SYNC qwen3_6_scripts/paged_attn.py: +311 lines, Triton bypass docs, _forward_decode_pytorch shape docs
- SYNC qwen3_6_scripts/qwen3_5.py: -72 lines, revert optimized MoE prefill to baseline (untested on BI-V100)
- KEEP Dockerfile: repo version has V2/Triton/head256 optimization patches not in baseline

Baseline commit: 1902c81fdd373943f17f5983eb8750758c7f4a69
Source: enginex-vllm-bi100-qwen36-main.zip (dev.modelhub.org.cn)

computility-run.yaml

@@ -10,7 +10,7 @@ command:
     - --max-model-len
     - '100000'
     - --gpu-memory-utilization
-    - '0.95'
+    - '0.9'
     - --trust-remote-code
     - -tp
     - '4'
@@ -19,10 +19,10 @@ command:
     - --disable-log-requests
     - --disable-frontend-multiprocessing
     - --max-num-batched-tokens
-    - '16384'
+    - '8192'
     - --enable-chunked-prefill
     - --max-seq-len-to-capture
-    - '65536'
+    - '32768'
     - --enable-auto-tool-choice
     - --tool-call-parser
     - qwen3_coder