feat: add retained managed transitions and reference-transparent execution

[piotr-blue]

Summary

Prepares the next Blue Language 3.1.0 release candidate with:

• authenticated, duplicate-preserving managed-transition receipts;
• retained managed-epoch replay without reinitializing or reprocessing source documents;
• occurrence-specific event continuity and verified cyclic successor evidence;
• lazy, verified reference-transparent reads and copy-on-write ordinary-reference patches;
• invocation-local, path-and-BlueId-bound reads through managed references;
• corrected checkpoint ownership, settlement, gas attribution and atomic rollback;
• updated Contracts conformance fixtures, semantic evidence and release documentation.

Compatibility

• Blue Language model/core/mapping, BlueId, BEX and Repository semantics are unchanged.
• Legacy state-only managed revisions and receipt-free result accessors remain supported.
• Java 8 bytecode targeting is retained.
• Contracts performs no ambient Timeline/history I/O.
• Managed occurrence paths remain mutation-opaque.
• List-backed/wildcard Process Embedded collections remain unsupported.

Verification

• 3,399 / 3,399 tests passed with no failures or skips.
• 429 / 429 conformance fixtures passed.
• clean build, finalQualityVerify, rcVerify and final API-baseline verification passed.
• All 7 staged Maven coordinates resolved in an isolated consumer.
• Runtime and source archives are reproducible.
• Final quality report contains zero release blockers.