v1.48.0

• Add codex:astra (GPT-6 Astra, gpt-6-astra) to the Codex model aliases with the max
  pair-role effort default, and make it the built-in plan reviewer and implementation reviewer
  for /stereo:plan, /stereo:implement, and /stereo:quick, replacing codex:sol in both
  review gates; the same-model reviewer substitution and the CLI-level plan-review default follow
• Document that claude:fable resolves to the harness's current Fable generation (Fable 5.1) and
  claude:opus to Opus 5, and that a specific generation cannot be pinned per role
• Require Codex CLI 0.153.1 or later for the default review gates, with a workspace-default
  fallback for older CLIs