Implement secretbox handlers and align gacha behavior

- Add secretbox API schemas, handlers, and routes for all/showDetail/pon/multi
- Load secretbox server data through the shared serverdata loader
- Fix rarity mapping and pool rules for SR/SSR/UR special boxes
- Implement thanks festival pool behavior, including UR guarantee and SSR/UR-only rates
- Correct animation-related fields such as is_hit and lowest_rarity, and add rare UR promotion animation

Signed-off-by: Sean Du <do4suki@gmail.com>

internal/handler/banner/helpers.go

@@ -0,0 +1,26 @@
+package banner
+
+import "reflect"
+
+func extractResultField(data any) any {
+	if data == nil {
+		return nil
+	}
+
+	value := reflect.ValueOf(data)
+	if value.Kind() == reflect.Pointer {
+		if value.IsNil() {
+			return nil
+		}
+		value = value.Elem()
+	}
+	if value.Kind() != reflect.Struct {
+		return data
+	}
+
+	field := value.FieldByName("Result")
+	if !field.IsValid() || !field.CanInterface() {
+		return data
+	}
+	return field.Interface()
+}

internal/handler/banner/list.go

@@ -0,0 +1,51 @@
+package banner
+
+import (
+	apibanner "honoka-chan/internal/handler/api/banner"
+	"honoka-chan/internal/middleware"
+	"honoka-chan/internal/router"
+	"honoka-chan/internal/session"
+
+	"github.com/gin-gonic/gin"
+)
+
+type bannerResp struct {
+	ResponseData any   `json:"response_data"`
+	ReleaseInfo  []any `json:"release_info"`
+	StatusCode   int   `json:"status_code"`
+}
+
+func list(ctx *gin.Context) {
+	ss := session.Get(ctx)
+	defer ss.Finalize()
+
+	data, err := apibanner.BannerApi("bannerList")
+	if ss.CheckErr(err) {
+		return
+	}
+
+	resp, ok := data.(interface {
+		GetResult() any
+	})
+	_ = resp
+	_ = ok
+
+	ss.Respond(bannerResp{
+		ResponseData: extractBannerResult(data),
+		ReleaseInfo:  []any{},
+		StatusCode:   200,
+	})
+}
+
+func extractBannerResult(data any) any {
+	if v, ok := data.(map[string]any); ok {
+		if result, ok := v["result"]; ok {
+			return result
+		}
+	}
+	return extractResultField(data)
+}
+
+func init() {
+	router.AddHandler("main.php", "POST", "/banner/bannerList", middleware.Common, list)
+}