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/schema/api/user/info.go

@@ -3,8 +3,8 @@ package userapischema
 import userschema "honoka-chan/internal/schema/user"
 
 type InfoResp struct {
-	Result     userschema.UserInfo `json:"result"`
-	Status     int                 `json:"status"`
-	CommandNum bool                `json:"commandNum"`
-	TimeStamp  int64               `json:"timeStamp"`
+	Result     userschema.UserInfoData `json:"result"`
+	Status     int                     `json:"status"`
+	CommandNum bool                    `json:"commandNum"`
+	TimeStamp  int64                   `json:"timeStamp"`
 }