build: restore runnable OUROBOROS foundation

[DivyamTalwar]

Summary

• restore every module imported by model/ouroboros.py
• add package metadata, Apache-2.0-consistent docs, and CI
• implement block-size enforcement/cropping and a CPU forward/backward smoke test
• replace unsupported empirical language with an explicit research-prototype status

Why first

The public tree could not import before this change. Optimization and feature work must build on a runnable baseline.

Acceptance

• clean editable install
• import plus forward/backward succeeds
• configuration and causal shift tests pass