fix: MSSQL login fails with "Unable to determine initial language" (#661) (#663)

Root cause: C bridge header had wrong FreeTDS constant values.
DBSETCHARSET was 7 (actually DBSETNATLANG), DBSETCHARSET is 10.
So "UTF-8" was being sent as the language, and no charset was set.

Fix: correct all dbsetlname constants to match FreeTDS master/include/sybdb.h,
add DBSETNATLANG=7 with "us_english" to the login packet.

Author: datlechin

Plugins/MSSQLDriverPlugin/CFreeTDS/include/sybdb.h

@@ -44,12 +44,17 @@ typedef struct loginrec LOGINREC;
 #define SYBDATETIMN     111
 #define SYBUNIQUE       36
 
-// Login property constants for dbsetlname() — values verified against FreeTDS 1.4 sybdb.h
-#define DBSETHOST   1
-#define DBSETUSER   2
-#define DBSETPWD    3
-#define DBSETAPP    5   // 4 is unused; real FreeTDS DBSETAPP = 5
-#define DBSETCHARSET 7  // Client charset for dbsetlname() — controls string encoding
+// Login property constants for dbsetlname() — values from FreeTDS master/include/sybdb.h
+#define DBSETHOST       1
+#define DBSETUSER       2
+#define DBSETPWD        3
+#define DBSETAPP        5
+#define DBSETBCP        6
+#define DBSETNATLANG    7
+#define DBSETCHARSET    10
+#define DBSETPACKET     11
+#define DBSETENCRYPT    12
+#define DBSETDBNAME     14
 
 // Convenience macros (match FreeTDS sybdb.h)
 #define DBSETLHOST(x, y)    dbsetlname((x), (y), DBSETHOST)

Plugins/MSSQLDriverPlugin/MSSQLPlugin.swift

@@ -196,6 +196,7 @@ private final class FreeTDSConnection: @unchecked Sendable {
         _ = dbsetlname(login, user, Int32(DBSETUSER))
         _ = dbsetlname(login, password, Int32(DBSETPWD))
         _ = dbsetlname(login, "TablePro", Int32(DBSETAPP))
+        _ = dbsetlname(login, "us_english", Int32(DBSETNATLANG))
         _ = dbsetlname(login, "UTF-8", Int32(DBSETCHARSET))
         _ = dbsetlversion(login, UInt8(DBVERSION_74))