fix: make comfy_aimdo import optional for AMD/ROCm GPU support

When comfy-aimdo is not installed (e.g. on AMD/ROCm systems), the bare
'import comfy_aimdo.control' at module level causes an immediate
ModuleNotFoundError that prevents ComfyUI from starting at all.

This change wraps the import in a try/except block. On ImportError, a
minimal no-op stub is installed in sys.modules so that subsequent
'import comfy_aimdo.*' statements in other modules (execution.py,
comfy/ops.py, comfy/model_patcher.py, comfy/pinned_memory.py, etc.)
also succeed without modification.

The stub returns False from all calls, which:
- Prevents comfy_aimdo.control.init_device() from signalling success
- Keeps comfy.memory_management.aimdo_enabled=False (its default)
- Allows all aimdo-guarded code paths to be safely skipped

Fixes #13182

main.py

@@ -31,7 +31,41 @@ setup_logger(log_level=args.verbose, use_stdout=args.log_stdout)
 
 faulthandler.enable(file=sys.stderr, all_threads=False)
 
-import comfy_aimdo.control
+try:
+    import comfy_aimdo.control
+except ImportError:
+    logging.info("comfy-aimdo not installed. DynamicVRAM will not be available.")
+    import types
+
+    class _AimdoStub:
+        """No-op stub for comfy_aimdo submodules when the package is not installed.
+
+        All attribute accesses return self and all calls return False (falsy),
+        which prevents any aimdo-guarded code paths from activating while still
+        allowing the import to succeed on non-NVIDIA hardware (e.g. AMD/ROCm).
+        """
+        def __getattr__(self, name):
+            return _AimdoStub()
+
+        def __call__(self, *args, **kwargs):
+            return False
+
+        def __bool__(self):
+            return False
+
+        def __int__(self):
+            return 0
+
+        def __float__(self):
+            return 0.0
+
+    _aimdo_pkg = types.ModuleType('comfy_aimdo')
+    for _submod_name in ('control', 'model_vbar', 'torch', 'host_buffer', 'model_mmap'):
+        _stub = _AimdoStub()
+        setattr(_aimdo_pkg, _submod_name, _stub)
+        sys.modules[f'comfy_aimdo.{_submod_name}'] = _stub
+    sys.modules['comfy_aimdo'] = _aimdo_pkg
+    import comfy_aimdo  # Now resolves to the stub from sys.modules
 
 if enables_dynamic_vram():
     comfy_aimdo.control.init()