patch 9.2.0206: MS-Window: stripping all CSI sequences

Problem:  MS-Window: stripping all CSI sequences
          (Ke Mao, after v9.2.0184)
Solution: Restore vtp_printf() to pass-through DECSUSR codes
          (Yasuhiro Matsumoto).

Patch 9.2.0184 discards all CSI sequences in mch_write() when VTP is
active to prevent unwanted DECRQM responses.  However, this also
removed the existing DECSCUSR pass-through, breaking cursor shape
changes (t_SI/t_SR/t_EI) on Windows Terminal.

Restore vtp_printf() pass-through for DECSCUSR (final byte 'q') while
continuing to discard other CSI sequences.

related: #19694
related: #11532
fixes:   #19750
closes:  #19755

Signed-off-by: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/os_win32.c

@@ -7443,7 +7443,9 @@ notsgr:
 	    // When USE_VTP is active, CSI sequences written through
 	    // write_chars() are interpreted by the console's VTP parser,
 	    // generating responses (e.g. DECRQM) that end up in the
-	    // input buffer as unwanted keystrokes.  Discard them.
+	    // input buffer as unwanted keystrokes.  Parse the sequence
+	    // and only pass through known safe ones (e.g. DECSCUSR for
+	    // cursor shape), discard the rest.
 	    if (USE_VTP)
 	    {
 		int l = 2;
@@ -7453,7 +7455,12 @@ notsgr:
 		    l++;
 		// skip the final byte (0x40-0x7E)
 		if (s + l < end && s[l] >= 0x40 && s[l] <= 0x7E)
+		{
+		    // DECSCUSR (cursor style): pass through to terminal
+		    if (s[l] == 'q')
+			vtp_printf("%.*s", l + 1, s);
 		    l++;
+		}
 		len -= l - 1;
 		s += l;
 	    }

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    206,
 /**/
     205,
 /**/