appview/{oauth,pages,state}: remove unused `AddAccount` session data

idk why is this added. Seems like it isn't used?

Signed-off-by: Seongmin Lee <[e-mail]>

appview/oauth/accounts.go

···
 }
 
 type AuthReturnInfo struct {
-	ReturnURL  string
-	AddAccount bool
+	ReturnURL string
 }
 
-func (o *OAuth) SetAuthReturn(w http.ResponseWriter, r *http.Request, returnURL string, addAccount bool) error {
+func (o *OAuth) SetAuthReturn(w http.ResponseWriter, r *http.Request, returnURL string) error {
 	session, err := o.SessStore.Get(r, AuthReturnName)
 	if err != nil {
 		return err
 	}
 
 	session.Values[AuthReturnURL] = returnURL
-	session.Values[AuthAddAccount] = addAccount
 	session.Options.MaxAge = 60 * 30
 	session.Options.HttpOnly = true
 	session.Options.Secure = !o.Config.Core.Dev
···
 	}
 
 	returnURL, _ := session.Values[AuthReturnURL].(string)
-	addAccount, _ := session.Values[AuthAddAccount].(bool)
 
 	return &AuthReturnInfo{
-		ReturnURL:  returnURL,
-		AddAccount: addAccount,
+		ReturnURL: returnURL,
 	}
 }
 

appview/oauth/consts.go

···
 	AccountsName         = "appview-accounts-v2"
 	AuthReturnName       = "appview-auth-return"
 	AuthReturnURL        = "return_url"
-	AuthAddAccount       = "add_account"
 	SessionHandle        = "handle"
 	SessionDid           = "did"
 	SessionId            = "id"

appview/pages/templates/user/login.html

···
                         </span>
                     </div>
                     <input type="hidden" name="return_url" value="{{ .ReturnUrl }}">
-                    <input type="hidden" name="add_account" value="{{ if .AddAccount }}true{{ end }}">
 
                     <button
                         class="btn w-full my-2 mt-6 text-base "

appview/state/login.go

···
 	case http.MethodPost:
 		handle := r.FormValue("handle")
 		returnURL := r.FormValue("return_url")
-		addAccount := r.FormValue("add_account") == "true"
 
 		// when users copy their handle from bsky.app, it tends to have these characters around it:
 		//
···
 			return
 		}
 
-		if err := s.oauth.SetAuthReturn(w, r, returnURL, addAccount); err != nil {
+		if err := s.oauth.SetAuthReturn(w, r, returnURL); err != nil {
 			l.Error("failed to set auth return", "err", err)
 		}