serialize 1.11.0 — precomputed compressed-float entry points

No wire change: every byte any existing call site produces is identical to 1.10.0, and the release-check's wire gate agrees. One addition.

Precomputed compressed-float entry points

The compressed-float path gains an additive precomputed form for callers that already know the per-field constants at build time, which is exactly what schema-generated code knows at generation time: serialize_compressed_float_params exposes the reference derivation (step count, wire width, delta from a min/max/resolution triple), serialize_compressed_float_precomputed_internal serializes with those constants passed in, and the serialize_compressed_float_precomputed macro is the house-idiom entry. The existing serialize_compressed_float signature and behavior are untouched; its body now composes the same audited home, and the proof is permanent rather than one-shot — a frozen verbatim copy of the pre-split body lives in the test section with a 3.5-million-check differential holding the composition to bit-identity against it, read side exhaustive through 16-bit widths. Tracking issue for the family rollout: mas-bandwidth/schema#82.