fix(CRITICAL): merge 26e6cb40 build pipeline + HEAD features — fix docker build

Key changes:
1. Dockerfile: restore ex_engine COPY + build steps from 26e6cb40 (working),
   add vendor_overrides staging, add ix_unified_bridge build step
2. computility-run.yaml: restore Sub168 proven params (max-model-len=80000,
   gpu-util=0.95, max-num-seqs=2, enforce-eager, dtype=half) + corex env vars
3. patch_ops.sh: make vendor_overrides missing non-fatal (skip instead of exit 2)
4. New: corex_so_loader.py — unified loader for 12 prebuilt .so
5. New: moe_fused_dispatch.py — 3-tier MoE dispatch (CCCL policy_selector)

Docker build was failing because:
- HEAD removed ex_engine COPY and all build steps
- patch_ops.sh exit 2 on missing vendor_overrides killed build
- computility-run.yaml had max-model-len=262144 causing OOM

26e6cb40 scored on competition platform. This commit restores that build
pipeline while adding the new HEAD features (prebuilt .so, vllm_overrides,
corex dispatch env vars).

qwen3_6_scripts/patch_ops.sh

@@ -110,9 +110,10 @@ echo "TRANSFORMERS_ROOT=${TRANSFORMERS_ROOT}"
 }
 
 VLLM_OVERRIDE_ROOT="./vendor_overrides/vllm"
+_HAS_OVERRIDES=true
 [[ -d "$VLLM_OVERRIDE_ROOT" ]] || {
-    printf 'vLLM override directory missing: %s\n' "$VLLM_OVERRIDE_ROOT" >&2
-    exit 2
+    printf '[WARN] vLLM override directory missing: %s — skipping override installs\n' "$VLLM_OVERRIDE_ROOT" >&2
+    _HAS_OVERRIDES=false
 }
 
 # --- Mirror path: base image may have TWO vllm installs ---
@@ -142,6 +143,7 @@ deploy_both() {
     [[ -n "$VLLM2" ]] && cp "$src" "${VLLM2}/${rel}" 2>/dev/null || true
 }
 
+if $_HAS_OVERRIDES; then
 build_stage "installing authoritative vLLM core block overrides"
 install_patch_file \
     "${VLLM_OVERRIDE_ROOT}/core/evictor_v2.py" \
@@ -170,6 +172,9 @@ install_patch_file \
 install_patch_file \
     "${VLLM_OVERRIDE_ROOT}/model_executor/layers/sampler.py" \
     "${VLLM_ROOT}/model_executor/layers/sampler.py"
+else
+build_stage "skipping vLLM core block overrides (vendor_overrides not found)"
+fi
 
 build_stage "installing hash-pinned CoreX 3.2.3 extensions"
 bash ./install_prebuilt_corex.sh "${VLLM_ROOT}"