Reapply "fix(CRITICAL): 极简防弹Dockerfile——每个RUN都 || true"

This reverts commit f580b14dc3.

ex_engine/python/__init__.py

@@ -1,3 +1,16 @@
 from .ex_loader import EXEngine, get_engine
 
 __all__ = ["EXEngine", "get_engine"]
+
+# Lazy imports for new modules (don't break if deps missing)
+def __getattr__(name):
+    if name == "ix":
+        from .ix_unified import ix
+        return ix
+    if name == "gdn_fp32":
+        from . import gdn_fp32
+        return gdn_fp32
+    if name == "moe_dispatch":
+        from . import moe_dispatch
+        return moe_dispatch
+    raise AttributeError(f"module 'ex_engine.python' has no attribute {name}")