[Group] Use modifier in group to add middleware not working

Use modifier to add middleware in group not working.

Reproduce code

```go
package main

import (
"context"
"net/http"
"net/http/httptest"

"github.com/danielgtaylor/huma/v2"
"github.com/danielgtaylor/huma/v2/adapters/humagin"
"github.com/gin-gonic/gin"
)

type TestOutput struct {
Body struct {
ID string `json:"id"`
}
}

type TestInput struct {
ID string `path:"id"`
}

func main() {
engine := gin.New()
api := humagin.New(engine, huma.DefaultConfig("My API", "1.0.0"))

v1 := huma.NewGroup(api, "/v1")

// For some reason, we can not use v1.UseMiddleware
v1.UseSimpleModifier(func(o *huma.Operation) {
o.Middlewares = append(o.Middlewares, func(ctx huma.Context, next func(huma.Context)) {
header := ctx.Header("X-Test")
if header == "" {
ctx.SetStatus(http.StatusUnauthorized)
return
}
next(ctx)
})
})

huma.Get(v1, "/test/{id}", func(ctx context.Context, input *TestInput) (*TestOutput, error) {
return &TestOutput{
Body: struct {
ID string `json:"id"`
}{
ID: input.ID,
},
}, nil
})

w := httptest.NewRecorder()
req, _ := http.NewRequest(http.MethodGet, "/v1/test/123", nil)
engine.ServeHTTP(w, req)

println(w.Code)
}
```

We do not pass the required test header, so Expected: 401 But Actual: 200.

We find the adapter do not respect the Operation's middlewares.

```go
func (a *ginAdapter) Handle(op *huma.Operation, handler func(huma.Context)) {
// Convert {param} to :param
path := op.Path
path = strings.ReplaceAll(path, "{", ":")
path = strings.ReplaceAll(path, "}", "")
a.router.Handle(op.Method, path, func(c *gin.Context) {
ctx := &ginCtx{op: op, orig: c}
handler(ctx)
})
}
```

And we change the adapter to the code below, the middleware worked.

```
func (a *ginAdapter) Handle(op *huma.Operation, handler func(huma.Context)) {
// Convert {param} to :param
path := op.Path
path = strings.ReplaceAll(path, "{", ":")
path = strings.ReplaceAll(path, "}", "")
a.router.Handle(op.Method, path, func(c *gin.Context) {
ctx := &ginCtx{op: op, orig: c}
op.Middlewares.Handler(handler)(ctx)
})
}
```

However, we're uncertain if this behavior is intentional. Implementing middleware via modifiers may lead to unintended side effects and should be avoided unless explicitly required by the design.

Please help, thanks.