feat(instance): refactor modify endpoint to support config types

- Change modify endpoint from `/modify/{field}` to `/modify` with POST
- Add support for two modification types: configFile and systemConfig
- Implement config file parsing using ini package for configFile type
- Update database schema to include name in update query
- Add comprehensive input validation and error handling
- Update documentation to reflect new API changes

router.go

@@ -47,13 +47,9 @@ func setupRoutes() {
 				return
 			}
 
-			if strings.HasPrefix(remainingPath, "modify/") {
-				parts := strings.SplitN(remainingPath, "/", 2)
-				if len(parts) == 2 {
-					field := parts[1]
-					ModifyInstanceHandler(w, r, field)
-					return
-				}
+			if remainingPath == "modify" { // Handle `/modify` by POST request
+				ModifyInstanceHandler(w, r)
+				return
 			}
 		}