Implement friend APIs and target profile support

- Add friend search/list/request/requestCancel/response/expel handlers and schemas
- Store friend relationships in user_friend and backfill default friend links at startup
- Auto-add the default user as a friend for newly created accounts
- Support target user_id in /api profile requests and return target profile data
- Make profile accessory_info optional to avoid zero-value accessory payloads
- Update login topInfo friend counters from friend relationship state

Signed-off-by: Sean Du <do4suki@gmail.com>

internal/startup/defaultuser.go

@@ -2,16 +2,16 @@ package startup
 
 import (
 	"honoka-chan/internal/handler/ghome/account"
+	usermodel "honoka-chan/internal/model/user"
 	"log"
 )
 
 const (
-	defaultPhone    = "1"
 	defaultPassword = "klsbgames"
 )
 
 func CreateDefaultUser() {
-	_, code, msg, created, err := account.AddUser(defaultPhone, defaultPassword, true)
+	_, code, msg, created, err := account.AddUser(usermodel.DefaultSystemPhone, defaultPassword, true)
 	if err != nil {
 		log.Fatalln("默认用户创建失败:", err.Error())
 	}
@@ -19,7 +19,7 @@ func CreateDefaultUser() {
 		log.Fatalf("默认用户创建失败: code=%d msg=%s", code, msg)
 	}
 	if created {
-		log.Printf("默认用户创建成功, 账号: %s, 密码: %s\n", defaultPhone, defaultPassword)
+		log.Printf("默认用户创建成功, 账号: %s, 密码: %s\n", usermodel.DefaultSystemPhone, defaultPassword)
 		return
 	}
 }