release: 1.6.0: 30-day send stats and optional auto level-2 rate limits

30-day sending statistics per domain and application, plus optional auto level-2 rate limits derived from average send rate.
Added:
  - Domain page **Sending statistics** card: total messages, peak and average
  - Level-2 rate limit **Manual** / **Auto** mode on domain and application
  - Domain export JSON now includes rate limits (`mode`, `auto_multiplier`,
Changed:
  - Auto mode uses the level-1 window (`RATE_LIMIT_WINDOW_SECONDS`); manual

Full detail: CHANGELOG.md (1.6.0).

cmd/panel/main.go

@@ -254,7 +254,7 @@ func run() error {
 	}
 
 	var wg sync.WaitGroup
-	errc := make(chan error, 3)
+	errc := make(chan error, 4)
 
 	roles := []struct {
 		name string
@@ -272,6 +272,10 @@ func run() error {
 				return days
 			})
 		}},
+		{"rate-limit-recalc", func(ctx context.Context) error {
+			runAutoRateLimitRecalc(ctx, cfg, st)
+			return nil
+		}},
 	}
 
 	for _, r := range roles {