[codex] Fix Fable goal ledger recovery

[baskduf]

Summary

• Reopen failed or blocked goal-ledger stories on next instead of reporting false completion or skipping ahead.
• Add regression tests for failed and blocked story recovery plus marketplace path validation.
• Standardize local docs, release, PR, and CI examples on python3.

Root Cause

The goal ledger only counted pending and in-progress stories when deciding whether work remained, so failed or blocked stories could be treated as complete. Tightening that logic without a reopen path would have made failed/blocked plans unrecoverable, so next now reopens the first failed or blocked story before later pending stories.

Verification

• python3 -m unittest discover -s tests -v
• python3 -m py_compile plugins/codex-fable5/skills/codex-fable5/scripts/codex_goals.py plugins/codex-fable5/skills/codex-fable5/scripts/fable_coverage.py plugins/codex-fable5/skills/codex-fable5/scripts/make_litellm_config.py tests/test_scripts.py
• python3 plugins/codex-fable5/skills/codex-fable5/scripts/fable_coverage.py
• git diff --cached --check

Review

• Self-review completed.
• Sub-agent review completed; initial findings were patched, final pass reported no blocking findings.