feat(domain): refine domain models with enums, enum serialization, and embedded metrics (SPEC-0002)

feat(domain): implement domain models specification and code (SPEC-0002)

refactor(config): finalize and freeze SPEC-0001 Configuration Manager

feat(config): implement Configuration Manager based on SPEC-0001

docs: establish design template, vocabulary rules, and freeze M0.0

docs: establish engineering principles and draft foundation RFC

docs: establish SPEC template and mandate SPEC-driven workflow