Add a debugger CLI for Haskell agent runs.
Requirements:
- New command (agentd debug or new omni-agent-debug binary).
- Load events.jsonl for a run and render prompt-build sections + hydration stats.
- Flags:
- --run-id <id>
- --full (show full section content)
- --json (emit structured JSON)
Output should include section ordering, source labels, token counts, and memory stats.
Added agentd debug command (agentd debug --run-id ... [--full] [--json]) to render prompt build/hydration events from events.jsonl; parses Trace.Event custom records and groups prompt_build sections. Tests: lint Omni/Agentd.hs; bild --test Omni/Agentd.hs