generate_synthetic: remove 36px gap after Korean char in type1

PGNet TCL connectivity breaks at large blank gaps, causing detection to
split single-line plates into 2 regions. Eval visualization confirmed
"37도1563" split into "37도"+"1563" at the gap location.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

data_gen/generate_synthetic.py

@@ -102,7 +102,7 @@ class LPGenerator:
         x0 = col
         for x in d:
             plate[row:row+83, col:col+56] = num[x]; col += 56
-        plate[row:row+83, col:col+60] = char[ch]; col += 60 + 36
+        plate[row:row+83, col:col+60] = char[ch]; col += 60
         for x in e:
             plate[row:row+83, col:col+56] = num[x]; col += 56
         x1 = col