Fill task records' tokens and Codex completion before commit

Two task.json gaps found by agent-scenarios:

• Claude Code task records never carried token_usage. The record copied the stop payload's usage, and Claude Code's SubagentStop has none. When the payload has no usage, compute it from the subagent's transcript.
• A Codex parent that waits for a child and commits before its own turn ends stored the child's record as still in flight, with no files or tokens. Codex's subagent-stop is provisional and only turn end or session end read the child rollouts. The git post-commit hook now runs the same inventory refresh for Codex sessions with in-flight records before condensation stores them.