fix: remove default empty string from UserKeychip.keychipId, document 1337 suffix

Agent-Logs-Url: https://github.com/MewoLab/AquaDX/sessions/543e2abd-831e-4d22-a4d3-4efb25251439

Co-authored-by: hykilpikonna <22280294+hykilpikonna@users.noreply.github.com>

AquaNet/src/pages/Home/SetupInstructions.svelte

@@ -20,6 +20,8 @@
   let isLoading = true;
   let isAdding = false;
 
+  // Format the keychip for use in segatools.ini.
+  // The '1337' suffix is appended to conform to the segatools keychip ID format requirement.
   function formatKeychipDisplay(k: string): string {
     return `${k.slice(0, 4)}-${k.slice(4)}1337`;
   }

src/main/java/icu/samnyan/aqua/sega/allnet/UserKeychip.kt

@@ -17,7 +17,7 @@ class UserKeychip(
     var user: AquaNetUser,
 
     @Column(unique = true, nullable = false, length = 32)
-    val keychipId: String = "",
+    val keychipId: String,
 )
 
 @Repository