Large content bodies hash entire payload in memory without streaming

[adamtheturtle]

Very large uploads cause high memory use; no documented limitation.

Refs: src/vws_auth_tools/init.py:78-79

[adamtheturtle]

Closing as won't do for current library scope.

vws-auth-tools is a thin helper for constructing Vuforia-style Authorization headers. Extra input validation, streaming hashes, and related protocol-hardening are not planned; callers are expected to pass well-formed credentials and request fields.