refactor: remove dead code and unused modules

Deletes thirteen orphaned files (APIs, utils, SCSS, modules) that are
no longer imported anywhere. Removes CustomCode enum, isValidSigId,
isValidUUID, and isMingdaoEmail which had no remaining callers.
Unexports the Thread component since it is only used within its file.

Author: OnCloud125252

app/(home)/apis/getPostComment.ts

@@ -38,7 +38,7 @@ function fixCoverUrl(cover: string) {
   return `${process.env.NEXT_PUBLIC_API_URL}/image/${cover}`;
 }
 
-export const Thread = ({ threadData }: { threadData: TThread }) => {
+const Thread = ({ threadData }: { threadData: TThread }) => {
   const user = threadData.user as User;
   const sig = threadData.sig as unknown as Sig;
   const isAnnouncement = sig._id === announcementSigId;

app/(home)/apis/getPostList.ts

@@ -1,48 +1,3 @@
-export const CustomCode = {
-  2000: "OK",
-
-  4000: "Not found",
-  4001: "Forbidden",
-
-  4010: "Invalid user",
-  4011: "Invalid body",
-  4012: "Invalid query",
-  4013: "Invalid JWT",
-  4015: "Invalid google access token",
-  4016: "Invalid image id",
-  4017: "Invalid user id",
-  4018: "Invalid post id",
-  4019: "Invalid sig id",
-  4020: "Invalid reply id",
-  4021: "Invalid custom id",
-  4022: "Custom id already exists",
-  4023: "Invalid content length",
-  4024: "Empty content",
-  4025: "Invalid hashtag",
-  4026: "Content size exceeded",
-  4027: "Failed to send email",
-  4028: "Already joined",
-  4029: "Already applied",
-  4030: "Not a member",
-  4031: "Already confirmed",
-  4032: "Invalid time range",
-
-  4100: "Error reading user from db",
-  4101: "Error writing user to db",
-  4102: "Error reading image from db",
-  4103: "Error writing image to db",
-  4104: "Error reading post from db",
-  4105: "Error writing post to db",
-  4106: "Error reading sig from db",
-  4107: "Error writing sig to db",
-  4108: "Error reading comment from db",
-  4109: "Error writing comment to db",
-  4110: "Error reading join request from db",
-  4111: "Error writing join request to db",
-
-  5000: "Unknown error",
-} as const;
-
 export const CustomStatus = {
   OK: 2000,