feat: add Thread Chat runtime skills MVP

[hifizz]

Summary

• add the add-thread-chat-skills OpenSpec change
• define runtime Skill catalog, sticky/one-shot activation and immutable version pinning
• specify slash-command UX, Fork/Retry/Edit semantics, prompt-prefix caching and Research Skill behavior

Base

• codex/feat-agent-observability-evaluation
• base commit: 48483101ad11bc84b611b615f423577633fedacb

Validation

• OpenSpec strict validation runs through .github/workflows/openspec.yml
• implementation and test evidence will be added to this draft PR as tasks complete

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Project	Deployment	Actions	Updated (UTC)
thread-chatbot	Error		Aug 30, 2026 11:47pm

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