webui: Add user birthday settings

- Store birth month and day in user_pref with default 10/18
- Migrate existing user_pref rows to fill missing birthday fields
- Expose birthday editing in the webui profile page
- Replace hardcoded birthday values in user info, top info, and product list responses
- Fix birthday month/day field alignment in the profile form

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

internal/handler/api/login/topinfo.go

@@ -57,7 +57,7 @@ func loginTopInfo(ctx *gin.Context) (res any, err error) {
 			NoticeMailDatetime:     now.Format("2006-01-02 15:04:05"),
 			FriendsApprovalWaitCnt: friendsApprovalWaitCnt,
 			FriendsRequestCnt:      friendsRequestCnt,
-			IsTodayBirthday:        false,
+			IsTodayBirthday:        ss.UserPref.IsBirthdayToday(now),
 			LicenseInfo: loginapischema.LicenseInfo{
 				LicenseList:  []any{},
 				LicensedInfo: []any{},