Release v0.8.0 single-GPU verl OPD runtime - #62

Summary

• add OPD v2 import/export for �erl-opd-v0.8-single-gpu-v1, preserving Parquet bytes, PEFT artifacts, identities, compiled plans and pure orward_kl_topk overrides
• keep teacher materialization, launchability and distributed execution fail-closed and independently reported
• publish a compiler-bound 72-field compatibility matrix and reposition README/docs around the pip-only single-GPU OPD path
• finalize release metadata at v0.8.0 without changing frozen scientific results

Validation

• 2178 passed, 9 skipped, 21 deselected; branch coverage 85.30%
• GPU: 8 passed; network: 15 passed
• pinned official verl conformance: 3 passed
• Ruff, format, mypy, actionlint, text/Markdown, release-state and strict MkDocs passed
• Playwright: 36 rendered SVG instances across 1440, 1024, 820 and 390 px; screenshots manually inspected
• wheel/sdist + Twine, clean core and [train] installs, pip-only OPD dry run, extracted-sdist suite/rebuild passed
• frozen calculator SHA-256 remains 53fc1d4d5b7adee09618d77ad62d4086ba56b78569832d6fc7c3bcd5c2695bbc

Boundaries

No benchmark was rerun or changed. No quality comparison was added. No distributed verl job ran, and the bundle remains launchable: false until exact student/teacher snapshots are materialized.