Module compression_policy 

Compression policy enum and storage tag for the Corpus aggregate.

Three mutually exclusive policies control how a [Corpus] stores embedding vectors:

Policy	Transform	StorageTag	Typical compression ratio
Compress	Full codec pipeline (rotate → quantize → optional residual)	U8	4–8×
Passthrough	Raw f32 bytes, no transformation	F32	1×
Fp16	Each f32 cast to f16 little-endian	F16	2×

The policy is set at corpus construction time and is immutable after the first insert call. Attempting to change it raises CorpusError::PolicyImmutable.

Enums

CompressionPolicy

Determines how vectors are stored in a Corpus.

StorageTag

Describes the physical byte layout of stored vector data.