fix(codex): classify injected turns and agent spawns

[drewstone]

Problem

Codex control messages were counted as human reactions, while recorded spawn_agent calls were omitted from subagent adoption unless a lifecycle event existed.

Change

• classify goal, subagent-result, and AGENTS instruction wrappers as injected
• use provider spawn tools as a fallback only when richer Task/Agent lifecycle spans are absent
• accept common subagent type fields and cover canonical-vs-fallback deduplication

Proof

• pnpm test: 17 files, 113 tests passed
• pnpm typecheck
• pnpm build
• same 20 Codex sessions: subagent spawns 0 -> 96; reaction signals 383 -> 33

[tangletools]

✅ Auto-approved drewstone PR — e680ea29

This PR was opened by the trusted drewstone account.
The full PR reviewer audit still runs separately and will publish findings if it detects issues.

_{tangletools · auto-approval · reason: drewstone_author · 2026-07-11T21:03:58Z}