chore🔧: move to go-admin-core v2

Every import of the module changes, not only the seven packages that
moved out of sdk/pkg: Go requires the major version in the path from v2
on. Both happen in one pass —

    go run github.com/go-admin-team/go-admin-core/tools/coreupgrade@v2.0.0 -w -v2 .
    go mod tidy

— which is the command the release notes give, run here as a consumer
would run it. 210 imports across 95 files.

The compatibility shims this used are gone in v2, so the paths that
moved had to move: sdk/pkg/captcha, sdk/pkg/jwtauth and its user
package, sdk/pkg/response and sdk/pkg/casbin.

The count of unformatted files is unchanged at 34, none of them touched
by this: the tool reformats a file only if it was already gofmt clean,
so a migration cannot disappear into whitespace.

app/admin/router/sys_role.go

@@ -2,7 +2,7 @@ package router
 
 import (
 	"github.com/gin-gonic/gin"
-	jwt "github.com/go-admin-team/go-admin-core/sdk/pkg/jwtauth"
+	jwt "github.com/go-admin-team/go-admin-core/v2/jwtauth"
 
 	"go-admin/app/admin/apis"
 	"go-admin/common/middleware"