store: give ecosystem traces their own table

Traces were written as facts. A single Praxis action wrote several of
them, so machine-rate rows crowded out the bounded fact readers that
humans and evaluation consume. The habit profile window of 2000 facts
and the memeval snapshot both filled with call records instead of what
Maven learned about the owner. Traces now go to ecosystem_traces, with
correlation, causation, duration and HTTP status as columns, pruned to
the most recent 5000. The new reader is exposed over IPC and rendered
as the Calls card on the ecosystem page, so it is a table someone
actually looks at.

Found in review of #84.

internal/ipc/server.go

@@ -132,6 +132,22 @@ func (a *storeAPI) CalendarEvents(ctx context.Context, from, to time.Time) ([]Fa
 	return out, nil
 }
 
+func (a *storeAPI) RecentEcosystemTraces(ctx context.Context, n int) ([]EcosystemTrace, error) {
+	trs, err := a.s.RecentEcosystemTraces(ctx, n)
+	if err != nil {
+		return nil, mapErr(err)
+	}
+	out := make([]EcosystemTrace, len(trs))
+	for i, tr := range trs {
+		out[i] = EcosystemTrace{
+			ID: tr.ID, Ts: tr.Ts, Service: tr.Service, Operation: tr.Operation,
+			Status: tr.Status, DurationMs: tr.DurationMs, CorrelationID: tr.CorrelationID,
+			CausationID: tr.CausationID, HTTPStatus: tr.HTTPStatus, Fields: tr.Fields,
+		}
+	}
+	return out, nil
+}
+
 func (a *storeAPI) RecentNudges(ctx context.Context, n int) ([]Nudge, error) {
 	ns, err := a.s.RecentNudges(ctx, n)
 	if err != nil {
@@ -774,6 +790,16 @@ var methodTable = map[Method]handlerFunc{
 		}
 		return out, nil
 	}),
+	MethodRecentEcoTraces: withParams(func(ctx context.Context, api CoreAPI, p nReq) ([]EcosystemTrace, error) {
+		out, err := api.RecentEcosystemTraces(ctx, p.N)
+		if err != nil {
+			return nil, err
+		}
+		if out == nil {
+			out = []EcosystemTrace{}
+		}
+		return out, nil
+	}),
 	MethodRecentNudges: withParams(func(ctx context.Context, api CoreAPI, p nReq) ([]Nudge, error) {
 		out, err := api.RecentNudges(ctx, p.N)
 		if err != nil {