Align living documentation with Determa State 0.2.0

[fruwe]

Closes #24

Summary

• pin the specification, conformance suite, Python engine, and Rust engine to their exact v0.2.0 releases
• update tutorial versions, dependency pins, normative links, and complete coverage for 75 specification sections and 111 core conformance cases
• add a runnable durable execution-checkpoint tutorial covering explicit store registration, SQLite persistence, accepted delivery, restart, processing, outbox persistence, and receipt replay
• update the persistence reference lab for all 108 released vectors and remove the two-digit conformance-case validator assumption

Validation

• make sources PYTHON=.venv/bin/python
• make check PYTHON=.venv/bin/python
• .venv/bin/python scripts/check_latest.py
• git diff --check

All checks passed from a fresh clone and isolated virtual environment. Determa State 0.2.0 remains the latest synchronized release.

Scope

Documentation only. This does not include candidate evaluation, timer/delivery host profiles, backup/relocation, remote clients, native effects, custom languages, or other unreleased behavior.