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/secretbox/showdetail.go

@@ -0,0 +1,78 @@
+package secretbox
+
+import (
+	"fmt"
+	"honoka-chan/internal/middleware"
+	"honoka-chan/internal/router"
+	secretboxschema "honoka-chan/internal/schema/secretbox"
+	"honoka-chan/internal/session"
+	honokautils "honoka-chan/internal/utils"
+
+	"github.com/gin-gonic/gin"
+)
+
+func showDetail(ctx *gin.Context) {
+	ss := session.Get(ctx)
+	defer ss.Finalize()
+
+	showDetailReq := secretboxschema.ShowDetailReq{}
+	err := honokautils.ParseRequestData(ctx, &showDetailReq)
+	if ss.CheckErr(err) {
+		return
+	}
+
+	data, err := showDetailData(showDetailReq.SecretBoxID)
+	if ss.CheckErr(err) {
+		return
+	}
+
+	ss.Respond(secretboxschema.ShowDetailResp{
+		ResponseData: data,
+		ReleaseInfo:  []any{},
+		StatusCode:   200,
+	})
+}
+
+func init() {
+	router.AddHandler("main.php", "POST", "/secretbox/showDetail", middleware.Common, showDetail)
+}
+
+func showDetailData(secretBoxID int) (secretboxschema.ShowDetailData, error) {
+	if secretBoxID <= 0 {
+		return secretboxschema.ShowDetailData{}, fmt.Errorf("invalid secret_box_id: %d", secretBoxID)
+	}
+
+	config, err := loadSecretBoxAllData()
+	if err != nil {
+		return secretboxschema.ShowDetailData{}, err
+	}
+
+	memberCategory, page, err := findSecretBoxPage(config, secretBoxID)
+	if err != nil {
+		return secretboxschema.ShowDetailData{}, err
+	}
+
+	result := secretboxschema.ShowDetailData{
+		URL: fmt.Sprintf("/webview.php/secretbox/detail?id=%d&no_title=1", secretBoxID),
+	}
+
+	switch page.SecretBoxInfo.SecretBoxType {
+	case 5:
+		buttons := make([]secretboxschema.ButtonTypeUnitLineUp, 0, len(page.ButtonList))
+		for _, button := range page.ButtonList {
+			buttons = append(buttons, secretboxschema.ButtonTypeUnitLineUp{
+				SecretBoxButtonType: button.SecretBoxButtonType,
+				SecretBoxName:       button.SecretBoxName,
+				UnitLineUp:          buildUnitLineUp(memberCategory, page, button),
+			})
+		}
+		result.ButtonTypeUnitLineUp = buttons
+	default:
+		if len(page.ButtonList) == 0 {
+			return secretboxschema.ShowDetailData{}, fmt.Errorf("secretbox %d has no buttons", secretBoxID)
+		}
+		result.UnitLineUp = buildUnitLineUp(memberCategory, page, page.ButtonList[0])
+	}
+
+	return result, nil
+}