TUI: add TuiPaste event class omitted from paste commit

Selective staging after the banner commit shifted hunk offsets and
this hunk fell outside the cutoff. It completes the previous commit:
without it the paste path references a missing name.

tai.py

@@ -8760,6 +8760,10 @@ class TuiClose(TuiEvent):
     name = "close"
 
 
+class TuiPaste(TuiEvent):
+    name = "paste"
+
+
 def tui_int(value, default=0):
     try:
         return int(value)