Remove context dependency from __hash__ and __eq__ (#1502)

Simplify Stream and Event hash/equality to use pointer comparison only,
avoiding expensive context lookups. This follows the cccl-rt principle
and fixes issues with wrapping foreign streams where context is unknown.

Closes #1480

Author: Andy-Jost

cuda_core/cuda/core/_event.pyx

@@ -172,7 +172,7 @@ cdef class Event:
             raise RuntimeError(explanation)
 
     def __hash__(self) -> int:
-        return hash((type(self), as_intptr(self._h_context), as_intptr(self._h_event)))
+        return hash((type(self), as_intptr(self._h_event)))
 
     def __eq__(self, other) -> bool:
         # Note: using isinstance because `Event` can be subclassed.

cuda_core/cuda/core/_stream.pyx

@@ -217,22 +217,12 @@ cdef class Stream:
         return (0, as_intptr(self._h_stream))
 
     def __hash__(self) -> int:
-        # Ensure context is initialized for hash consistency
-        Stream_ensure_ctx(self)
-        return hash((as_intptr(self._h_context), as_intptr(self._h_stream)))
+        return hash(as_intptr(self._h_stream))
 
     def __eq__(self, other) -> bool:
         if not isinstance(other, Stream):
             return NotImplemented
-        cdef Stream _other = <Stream>other
-        # Fast path: compare handles first
-        if as_intptr(self._h_stream) != as_intptr(_other._h_stream):
-            return False
-        # Ensure contexts are initialized for both streams
-        Stream_ensure_ctx(self)
-        Stream_ensure_ctx(_other)
-        # Compare contexts as well
-        return as_intptr(self._h_context) == as_intptr(_other._h_context)
+        return as_intptr(self._h_stream) == as_intptr((<Stream>other)._h_stream)
 
     @property
     def handle(self) -> cuda.bindings.driver.CUstream: