fix: preserve typed growth report revisions

internal/growthreport/model.go

@@ -2,6 +2,7 @@ package growthreport
 
 import (
 	"encoding/json"
+	"fmt"
 	"time"
 )
 
@@ -44,11 +45,12 @@ type Usage struct {
 
 type Report struct {
 	ReportID              string          `json:"reportId"`
+	Revision              int             `json:"revision"`
 	Status                Status          `json:"status"`
 	Scope                 Scope           `json:"scope"`
 	HorizonDays           int             `json:"horizonDays"`
 	ForecastStartDate     *time.Time      `json:"forecastStartDate,omitempty"`
-	DeterministicEvidence json.RawMessage `json:"deterministicEvidence"`
+	DeterministicEvidence json.RawMessage `json:"deterministicEvidence,omitempty"`
 	AICopy                *AICopy         `json:"aiCopy,omitempty"`
 	FailureCode           *string         `json:"failureCode,omitempty"`
 	Cached                bool            `json:"cached"`
@@ -79,3 +81,10 @@ type CreateRequest struct {
 	TerminalID string `json:"terminalId"`
 	Refresh    bool   `json:"refresh"`
 }
+
+type RefreshLimitError struct{ NextRefreshAt time.Time }
+
+func (e *RefreshLimitError) Error() string {
+	return fmt.Sprintf("%s: next refresh at %s", ErrRefreshLimited, e.NextRefreshAt.Format(time.RFC3339))
+}
+func (e *RefreshLimitError) Unwrap() error { return ErrRefreshLimited }