feat(delivery): extend MySQL delivery parameters and tighten resource bounds

- Add topology/port/data_disk, DB options and 8 advanced parameters
  with whitelist validation, rendered via extra_vars into the playbook
- Hybrid port allocation over pool 13306-13999
- Tighten bounds: memory 2048-65536 MiB, storage 20-2000 GiB

server/internal/config/config.go

@@ -70,6 +70,7 @@ type Config struct {
 	DeliveryGlobalLimit      int
 	DeliveryTargetLimit      int
 	DeliveryBusinessLimit    int
+	DeliveryDataDisks        []string
 }
 
 func Load() Config {
@@ -138,6 +139,7 @@ func Load() Config {
 		DeliveryGlobalLimit:      envInt("DELIVERY_GLOBAL_LIMIT", 2),
 		DeliveryTargetLimit:      envInt("DELIVERY_TARGET_LIMIT", 2),
 		DeliveryBusinessLimit:    envInt("DELIVERY_BUSINESS_LIMIT", 1),
+		DeliveryDataDisks:        envCSV("DELIVERY_DATA_DISKS", "/data"),
 	}
 }
 
@@ -241,6 +243,14 @@ func envInt(key string, fallback int) int {
 	return parsed
 }
 
+func envCSV(key, fallback string) []string {
+	items := splitCSV(env(key, fallback))
+	if len(items) == 0 {
+		items = splitCSV(fallback)
+	}
+	return items
+}
+
 func defaultPublicBaseURL(httpAddr string) string {
 	addr := strings.TrimSpace(httpAddr)
 	if addr == "" {