* fix: use chunked read for integration and preset manifest hash
Replace unbounded fh.read() with chunked iteration to prevent excessive
memory allocation on large or corrupted manifest files. Applies to both
integrations/catalog.py and presets/__init__.py get_hash() methods.
* test: verify full hash value in get_hash() tests to cover chunked path
The existing tests only checked the sha256: prefix, which would pass
even if the chunked hash was broken. Now verify the complete hash
matches hashlib.sha256(content).hexdigest() to exercise the multi-chunk
path introduced by the chunked read change.
Quratulain-bilal
d3f9212701