fix(issue-170): restore Codex usage across rollout schema changes

[pacphi]

Summary

• normalize legacy event_msg user_message/agent_message and current item_completed UserMessage/AgentMessage rollouts into one prompt/response contract
• bump the derived cache schema to 10 and reparse stale or incomplete Codex cache entries
• expose bounded Codex parse-yield diagnostics, including zero and partial response yield
• add additive byDay[day].sessionsActive while preserving first-billed sessions
• update dashboard tooltips, transcript/metrics references, and ADR-0009/ADR-0023

Validation

• pnpm run check
• focused Codex, aggregation, cache, and citation tests
• current post-update Codex rollout files verified locally

Issue: #170