test: 回退Docker context到26e6cb40完全一致——验证竞赛平台build

Dockerfile/qwen3_6_scripts/ex_engine/computility-run.yaml 全部
还原到26e6cb40的精确内容。删除所有26e6cb40不存在的新增文件
(prebuilt/*.so, wheels/*.whl, vendor_overrides/, 新增.cu/.sh等)。

目的：确认26e6cb40的文件内容在当前git状态下仍能通过竞赛平台build。
如果通过，说明问题在新增文件中；如果不通过，说明问题在git仓库层面。

ex_engine/find_ixformer_symbols.py

@@ -1,55 +0,0 @@
-#!/usr/bin/env python3
-"""Find which .so files export ixformer::infer symbols."""
-import subprocess, glob, os
-
-targets = ["silu_and_mul", "rms_norm", "ixformer_linear", "topk_softmax",
-           "xllm_paged_attention", "xllm_reshape_and_cache",
-           "moe_w16a16_group_gemm", "residual_rms_norm"]
-
-search_dirs = [
-    "/usr/local/corex/lib64",
-    "/usr/local/corex/lib",
-    "/usr/local/corex-3.2.3/lib64",
-    "/usr/local/corex-3.2.3/lib",
-    "/usr/local/lib",
-]
-
-so_files = []
-for d in search_dirs:
-    so_files.extend(glob.glob(os.path.join(d, "**/*.so*"), recursive=True))
-
-print(f"Scanning {len(so_files)} .so files...")
-
-for target in targets:
-    found = False
-    for so in so_files:
-        try:
-            out = subprocess.run(["nm", "-D", so], capture_output=True, text=True, timeout=5)
-            if target in out.stdout:
-                # Get the full symbol name
-                for line in out.stdout.split('\n'):
-                    if target in line and ' T ' in line:
-                        sym = line.split()[-1]
-                        print(f"✓ {target}: {os.path.basename(so)}  [{sym[:80]}]")
-                        found = True
-                        break
-                if found:
-                    break
-        except:
-            pass
-    if not found:
-        # Try with grep on all lines (U = undefined, T = defined)
-        for so in so_files:
-            try:
-                out = subprocess.run(["nm", "-D", so], capture_output=True, text=True, timeout=5)
-                for line in out.stdout.split('\n'):
-                    if target in line:
-                        print(f"? {target}: {os.path.basename(so)}  [{line.strip()[:100]}]")
-                        found = True
-                        break
-                if found:
-                    break
-            except:
-                pass
-    if not found:
-        print(f"✗ {target}: NOT FOUND in any .so")