Füge Modelle für Flows, FlowRuns, TaskRuns, WorkPools, WorkQueues, Deployments, Variablen, FlowRunStates, Logs, und Blocks samt zugehöriger Unmarshal-Logik und Zeitfeld-Unterstützung hinzu; ergänze Tests für die FlowRunStates-Service-Methoden.

pkg/models/time.go

@@ -0,0 +1,45 @@
+package models
+
+import (
+	"encoding/json"
+	"time"
+)
+
+// parseOptionalTime parses a time string, returning nil for empty strings.
+// Supports RFC3339Nano and RFC3339 formats used by the Prefect API.
+func parseOptionalTime(s string) (*time.Time, error) {
+	if s == "" {
+		return nil, nil
+	}
+	t, err := time.Parse(time.RFC3339Nano, s)
+	if err != nil {
+		t, err = time.Parse(time.RFC3339, s)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &t, nil
+}
+
+// optTime handles JSON unmarshaling of nullable time fields that may be
+// represented as empty strings or JSON null by the Prefect API.
+type optTime struct {
+	V *time.Time
+}
+
+func (o *optTime) UnmarshalJSON(data []byte) error {
+	if string(data) == "null" {
+		o.V = nil
+		return nil
+	}
+	var s string
+	if err := json.Unmarshal(data, &s); err != nil {
+		return err
+	}
+	v, err := parseOptionalTime(s)
+	if err != nil {
+		return err
+	}
+	o.V = v
+	return nil
+}