fix(mouse): mouseclick after conceal_lines is miscalculated #33451

Problem:  Computed buffer line for mouse position does not take into
          account concealed lines on the reached row.

Solution: Adjust for concealed lines at the end of the loop computing
          the buffer position.

src/nvim/mouse.c

@@ -9,6 +9,7 @@
 #include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cursor.h"
+#include "nvim/decoration.h"
 #include "nvim/drawscreen.h"
 #include "nvim/edit.h"
 #include "nvim/eval.h"
@@ -1659,6 +1660,12 @@ bool mouse_comp_pos(win_T *win, int *rowp, int *colp, linenr_T *lnump)
     lnum++;
   }
 
+  // Mouse row reached, adjust lnum for concealed lines.
+  while (decor_conceal_line(win, lnum - 1, false)) {
+    lnum++;
+    hasFolding(win, lnum, NULL, &lnum);
+  }
+
   if (!retval) {
     // Compute the column without wrapping.
     int off = win_col_off(win) - win_col_off2(win);