fix: open the sign-in page instead of creating a new account on a fresh client

With no remembered account, the 2023 title screen creates a brand-new
account (grant_type create_account). On a server with sign-ups off that
fails and the title screen retries forever. PC (ClientMod) and Quest
now open the sign-in page instead, so players log into their existing
DorkNet account. AutoCreateAccount = true keeps Rec Room's behaviour.

Also replaces a literal NUL byte in the Quest config loader with '\0'.

DorkNet.Quest/targets/20230317-2128210.json

@@ -111,6 +111,12 @@
       "length": 412,
       "fingerprint": "0xb12b0044ac4f844f",
       "why": "Log-only: prints the quit code and caller."
+    },
+    "title_auto_login": {
+      "rva": 58892048,
+      "length": 668,
+      "fingerprint": "0x83bebb9a30983b33",
+      "why": "Title-screen auto-login. With no remembered account (null) it creates a new account; unless AutoCreateAccount is on, open the sign-in page instead."
     }
   }
 }

DorkNet.Quest/targets/spec.json

@@ -114,6 +114,12 @@
       "class": "public class SessionManager ",
       "method": "public static void TryApplicationQuit(int DKOGJICFAEP)",
       "why": "Log-only: prints the quit code and caller."
+    },
+    {
+      "id": "title_auto_login",
+      "class": "public class TitleScreenFlowModel ",
+      "method": "private LDGADANDBIO IAKHIJIHAPJ(LBNJFPOLCDL.MDGJJCFGJNF AJCKAHHJDEN)",
+      "why": "Title-screen auto-login. With no remembered account (null) it creates a new account; unless AutoCreateAccount is on, open the sign-in page instead."
     }
   ]
 }