fix(cap): keep only /api/v1/cap routes

Drop the unversioned /api/cap aliases so Challenge and Redeem exist only under /api/v1/cap.

backend/plugins/domain/cap/handlers.go

@@ -20,7 +20,8 @@ import (
 // @Param request body challengeRequest false "可选范围限制参数"
 // @Success 200 {object} response.Any{data=cap.ChallengeResponse} "成功返回 PoW 难题"
 // @Failure 500 {object} response.Any "内部服务错误"
-// @Router /api/cap/challenge [post]
+// @Router /api/v1/cap/challenge [get]
+// @Router /api/v1/cap/challenge [post]
 func Challenge(c *gin.Context) {
 	var req challengeRequest
 	_ = c.ShouldBind(&req) // 允许不传 body，默认使用 login scope
@@ -54,7 +55,7 @@ func Challenge(c *gin.Context) {
 // @Success 200 {object} response.Any{data=cap.RedeemResponse} "核销成功，返回 X-Cap-Token"
 // @Failure 400 {object} response.Any "参数错误或核销失败"
 // @Failure 500 {object} response.Any "内部服务错误"
-// @Router /api/cap/redeem [post]
+// @Router /api/v1/cap/redeem [post]
 func Redeem(c *gin.Context) {
 	var req redeemRequest
 	if err := c.ShouldBindJSON(&req); err != nil {

backend/plugins/domain/cap/plugin.go

@@ -86,11 +86,7 @@ func (p *Plugin) Apply(ctx *core.Context) error {
 		capGroup.POST("/challenge", Challenge)
 		capGroup.POST("/redeem", Redeem)
 	}
-
-	legacy := ctx.Router().Group("/api/cap")
-	legacy.POST("/challenge", Challenge)
-	legacy.POST("/redeem", Redeem)
-	ctx.Router().RegisterWhitelist("/api/cap/challenge", "/api/cap/redeem")
+	ctx.Router().RegisterWhitelist("/api/v1/cap/challenge", "/api/v1/cap/redeem")
 
 	// Register Settings Schemas
 	ctx.Settings().Register(extpoints.SettingSchema{

backend/plugins/domain/cap/plugin_captcha_contract_test.go

@@ -34,15 +34,18 @@ func TestApplyRegistersUnversionedCapRoutes(t *testing.T) {
 		t.Fatal(err)
 	}
 	want := map[string]bool{
+		"GET /api/v1/cap/challenge":  false,
 		"POST /api/v1/cap/challenge": false,
-		"POST /api/cap/challenge":    false,
-		"POST /api/cap/redeem":       false,
+		"POST /api/v1/cap/redeem":    false,
 	}
 	for _, rd := range ctx.Router().Routes() {
 		key := rd.Method + " " + rd.Path
 		if _, ok := want[key]; ok {
 			want[key] = true
 		}
+		if key == "POST /api/cap/challenge" || key == "POST /api/cap/redeem" {
+			t.Errorf("legacy route must not exist: %s", key)
+		}
 	}
 	for key, ok := range want {
 		if !ok {