Fix per-process image cache key equality

[fallintoplace]

Summary

Fix per-process image cache key equality so entries with the same tile location but different file hashes do not alias.

What changed

• compare both file_hash and location_hash in the per-process cache key equality functor
• add a CPU-only regression test that inserts two cache entries with the same tile location and different file hashes
• wire the new regression test into cucim_tests

Why

The per-process cache hash already mixed file_hash and location_hash, but equality only compared location_hash.

That allowed different files or IFDs with matching tile coordinates to be treated as the same cache key, which could return the wrong cached tile or reject a valid insert as a duplicate.

Validation

• reviewed the per-process cache hash/equality implementation and confirmed the mismatch with the shared-memory cache comparator
• added a regression test through the public cache manager API to exercise the collision case directly
• attempted local CMake configure, but this machine cannot build the project because FindCUDAToolkit fails to locate nvcc

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