fix: ex_engine.python subpackage + flash_qla_sm70 deploy + vllm v0.5.5 MoE kernels

真机验证发现的问题:
1. qwen3_5.py 做 'from ex_engine.python.ix_bridge' 但包结构是 ex_engine.ix_bridge
   → 创建 python/ 子目录 + symlinks
2. flash_qla_sm70 只部署到 /workspace 没有到 vllm models 目录
   → 显式 cp -r 到 VLLM/model_executor/models/
3. 从 vllm v0.5.5 搬 MoE CUDA kernels (torch::Tensor API):
   - topk_softmax_kernels.cu (506行, CUB BlockReduce)
   - moe_align_block_size_kernels.cu (134行)
   - moe_pybind.cpp (pybind11 入口)

真机验证结果:
  ✓ ix_bridge import OK, available=True
  ✓ topk_softmax (64 experts, top8) OK — CUDA kernel 命中
  ✓ ix_full_bridge silu_and_mul OK
  ✓ qwen3_5.py import OK
  ✓ ex_engine build 2/2 factors
  ✓ moe_topk_softmax_v3.so 编译成功
  ✓ flash_qla_sm70_gdn_strided.so 编译成功
  ✗ 单卡 32GB OOM (正常, 竞赛 4卡 tp=4)

ex_engine/csrc/moe_v055/dispatch_utils.h

@@ -0,0 +1,35 @@
+/*
+ * Adapted from
+ * https://github.com/pytorch/pytorch/blob/v2.0.1/aten/src/ATen/Dispatch.h
+ */
+#pragma once
+
+#include <torch/all.h>
+
+#define VLLM_DISPATCH_CASE_FLOATING_TYPES(...)         \
+  AT_DISPATCH_CASE(at::ScalarType::Float, __VA_ARGS__) \
+  AT_DISPATCH_CASE(at::ScalarType::Half, __VA_ARGS__)  \
+  AT_DISPATCH_CASE(at::ScalarType::BFloat16, __VA_ARGS__)
+
+#define VLLM_DISPATCH_FLOATING_TYPES(TYPE, NAME, ...) \
+  AT_DISPATCH_SWITCH(TYPE, NAME, VLLM_DISPATCH_CASE_FLOATING_TYPES(__VA_ARGS__))
+
+#define VLLM_DISPATCH_CASE_FLOATING_AND_BYTE_TYPES(...)   \
+  AT_DISPATCH_CASE(at::ScalarType::Float, __VA_ARGS__)    \
+  AT_DISPATCH_CASE(at::ScalarType::Half, __VA_ARGS__)     \
+  AT_DISPATCH_CASE(at::ScalarType::BFloat16, __VA_ARGS__) \
+  AT_DISPATCH_CASE(at::ScalarType::Byte, __VA_ARGS__)
+
+#define VLLM_DISPATCH_FLOATING_AND_BYTE_TYPES(TYPE, NAME, ...) \
+  AT_DISPATCH_SWITCH(TYPE, NAME,                               \
+                     VLLM_DISPATCH_CASE_FLOATING_AND_BYTE_TYPES(__VA_ARGS__))
+
+#define VLLM_DISPATCH_CASE_INTEGRAL_TYPES(...)         \
+  AT_DISPATCH_CASE(at::ScalarType::Byte, __VA_ARGS__)  \
+  AT_DISPATCH_CASE(at::ScalarType::Char, __VA_ARGS__)  \
+  AT_DISPATCH_CASE(at::ScalarType::Short, __VA_ARGS__) \
+  AT_DISPATCH_CASE(at::ScalarType::Int, __VA_ARGS__)   \
+  AT_DISPATCH_CASE(at::ScalarType::Long, __VA_ARGS__)
+
+#define VLLM_DISPATCH_INTEGRAL_TYPES(TYPE, NAME, ...) \
+  AT_DISPATCH_SWITCH(TYPE, NAME, VLLM_DISPATCH_CASE_INTEGRAL_TYPES(__VA_ARGS__))