[codex] Read development notes before acting

[Yuimi-chaya]

What changed

• split development-note behavior into independent read and write gates
• require reading relevant notes before diagnosis, planning, solution selection, implementation, resumption, or direction changes
• recover similar scenarios, user preferences, rejected approaches, overall direction, authoritative state, evidence, risks, and next actions
• update the reference AGENTS rule, UI metadata, documentation, changelog, and repository validation

Why

The previous Skill strongly specified when and how to write notes, but did not require agents to read existing project memory before acting. That allowed repeated investigations, ignored user preferences, and retries of already rejected solutions.

Validation

• repository validator passed: 15 text files and 22 interview questions
• repository Skill validator passed
• installed Skill validator passed
• repository and installed Skill files are byte-identical and UTF-8 without BOM
• independent forward test read the development note first, recovered the earlier line-ending incident and sequencing constraints, and refused an unsafe overwrite