refactor(cuda.core): tighten memory-attr query

Address review feedback on _buffer.pyx:

- Restore `inline` on `_init_mem_attrs` and `_query_memory_attrs`.
- Set `out.is_managed = (is_managed != 0)` once outside the if/elif,
  rather than per-branch (driver leaves the attribute zero for
  non-managed pointers, so all three branches converged on the same
  value anyway).
- Add a TODO noting that HMM/ATS-enabled sysmem should also report
  `is_managed=True`; the CU_POINTER_ATTRIBUTE_IS_MANAGED query does
  not capture that yet.

The Cython modernization of _managed_memory_ops.pyx (cimport cydriver,
IF/ELSE for the 12/13 ABI split) is folded into Tasks 5-8 where the
public API is being rewritten anyway; doing it here would mean
rewriting the same call sites twice.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cuda_core/cuda/core/_memory/_buffer.pyx

@@ -422,14 +422,14 @@ cdef class Buffer:
 
 # Memory Attribute Query Helpers
 # ------------------------------
-cdef void _init_mem_attrs(Buffer self):
+cdef inline void _init_mem_attrs(Buffer self):
     """Initialize memory attributes by querying the pointer."""
     if not self._mem_attrs_inited:
         _query_memory_attrs(self._mem_attrs, as_cu(self._h_ptr))
         self._mem_attrs_inited = True
 
 
-cdef int _query_memory_attrs(
+cdef inline int _query_memory_attrs(
     _MemAttrs& out,
     cydriver.CUdeviceptr ptr
 ) except -1 nogil:
@@ -456,12 +456,15 @@ cdef int _query_memory_attrs(
         ret = cydriver.cuPointerGetAttributes(3, attrs, <void**>vals, ptr)
     HANDLE_RETURN(ret)
 
+    # TODO: HMM/ATS-enabled sysmem should also report is_managed=True; the
+    # CU_POINTER_ATTRIBUTE_IS_MANAGED query does not capture that yet.
+    out.is_managed = is_managed != 0
+
     if memory_type == 0:
         # unregistered host pointer
         out.is_host_accessible = True
         out.is_device_accessible = False
         out.device_id = -1
-        out.is_managed = False
     elif (
         is_managed
         or memory_type == cydriver.CUmemorytype.CU_MEMORYTYPE_HOST
@@ -470,12 +473,10 @@ cdef int _query_memory_attrs(
         out.is_host_accessible = True
         out.is_device_accessible = True
         out.device_id = device_id
-        out.is_managed = is_managed != 0
     elif memory_type == cydriver.CUmemorytype.CU_MEMORYTYPE_DEVICE:
         out.is_host_accessible = False
         out.is_device_accessible = True
         out.device_id = device_id
-        out.is_managed = False
     else:
         with cython.gil:
             raise ValueError(f"Unsupported memory type: {memory_type}")