term: cursor-left: reduce move count by one when lcf=true

When lcf is true, cursor is actually beyond the right margin, but the
stored coordinate is at the margin.

This means we need to reduce the number of cells to move the cursor by
one.

This fixes an issue where e.g. backspacing when the cursor is at the
right margin erased the next-to-last character instead of the last
character.

CHANGELOG.md

@@ -43,6 +43,8 @@
   that it is (much) slower compared to previous foot versions. Use the
   **scrollback.multiplier** option in `foot.ini` if you find the new
   speed too slow (https://codeberg.org/dnkl/foot/issues/144).
+* Cursor left movements moving cursor to wrong location when cursor is
+  “beyond” the right margin.
 
 
 ### Security

terminal.c

@@ -1728,6 +1728,11 @@ term_cursor_home(struct terminal *term)
 void
 term_cursor_left(struct terminal *term, int count)
 {
+    if (unlikely(term->grid->cursor.lcf))
+        count--;
+
+    assert(count >= 0);
+
     int move_amount = min(term->grid->cursor.point.col, count);
     term->grid->cursor.point.col -= move_amount;
     assert(term->grid->cursor.point.col >= 0);