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/handler/api/login/login.go

@@ -2,12 +2,14 @@ package login
 
 import (
 	"fmt"
+
+	"github.com/gin-gonic/gin"
 )
 
-func LoginApi(action string) (res any, err error) {
+func LoginApi(ctx *gin.Context, action string) (res any, err error) {
 	switch action {
 	case "topInfo":
-		res, err = loginTopInfo()
+		res, err = loginTopInfo(ctx)
 	case "topInfoOnce":
 		res, err = loginTopInfoOnce()
 	default: