feat(tb-lf): add trace-metrics command, rename metrics to daily-metrics

[trogulja]

Summary

• Rename metrics → daily-metrics (backward-compatible metrics alias preserved)
• New trace-metrics command consuming the DevPortal /trace_metrics API:
  • Aggregated view with --group-by day|outcome|agent_type|flag:<name>
  • Per-trace detail: tb-lf trace-metrics <trace_id> — shows metrics, tool breakdown, flags, triage
• Deserialization types + 3 unit tests for response parsing

Usage

# Aggregated (default: group by day, last 7 days)
tb-lf trace-metrics --from 7d

# Group by outcome
tb-lf trace-metrics --group-by outcome --from 14d

# A/B test a feature flag
tb-lf trace-metrics --group-by flag:coreAgents --from 7d

# Per-trace detail
tb-lf trace-metrics abc123def456

Related

• productiveio/devportal#250 — fix: date filtering uses trace timestamp (merged)
• productiveio/devportal#251 — fix: sync token counts + agent_type from Langfuse v2 API (pending)

Test plan

• cargo clippy — clean
• cargo fmt — clean
• cargo test — 3 new deserialization tests pass
• Manually tested all commands against production data

🤖 Generated with Claude Code