feat: rename gpt-5-4-prompting skill to gpt-5-5-prompting

[Flex83]

Summary

Renames the internal prompting guidance skill from gpt-5-4-prompting to gpt-5-5-prompting and updates its content to reflect GPT-5.5 best practices.

Changes

• Skill renamed: plugins/codex/skills/gpt-5-4-prompting/ → plugins/codex/skills/gpt-5-5-prompting/
• Skill content rewritten for GPT-5.5: outcome-first prompts, revised reasoning effort defaults, Personality block, text.verbosity, preamble pattern for tool-heavy runs, updated phase parameter guidance, stopping conditions and retrieval budgets, validation defaults
• References updated in agents/codex-rescue.md and skills/codex-cli-runtime/SKILL.md
• Tests updated in tests/commands.test.mjs to match new skill name and content

Motivation

GPT-5.5 reasons more efficiently than GPT-5.4 and responds better to shorter, outcome-focused prompts. The existing gpt-5-4-prompting skill carried forward process-heavy patterns optimised for GPT-5.4 that produce mechanical, over-structured answers on GPT-5.5. This update aligns the skill with current OpenAI prompt guidance (developers.openai.com, May 2026).

Testing

All 8 plugin tests pass: node --test tests/commands.test.mjs

[Flex83]

Closing — local-only changes, no OpenAI contribution intended. Apologies for the noise.