fix: bullet padding indenting heading borders

## Details

Issue: #297

Tree sitter parser has the last list item extending to the next section.
Since heading borders are added as overlay lines when space is available
they will end up getting the padding that was added there for the list
item. Fix is to have a special case for the last line in a list when it
is empty, not the best but seems to work well enough.

Author: MeanderingProgrammer

doc/render-markdown.txt

@@ -1,4 +1,4 @@
-*render-markdown.txt*          For 0.10.0         Last change: 2025 January 10
+*render-markdown.txt*          For 0.10.0         Last change: 2025 January 14
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*

lua/render-markdown/health.lua

@@ -5,7 +5,7 @@ local state = require('render-markdown.state')
 local M = {}
 
 ---@private
-M.version = '7.8.6'
+M.version = '7.8.7'
 
 function M.check()
     M.start('version')

lua/render-markdown/render/list_item.lua

@@ -121,17 +121,31 @@ function Render:padding(root)
         return
     end
     local left_col = root ~= nil and root.start_col or self.node.start_col
-
-    local next_list = self.node:child('list')
-    local end_row = next_list ~= nil and next_list.start_row or self.node.end_row
-
-    for row = self.node.start_row, end_row - 1 do
+    for row = self.node.start_row, self:end_row(root) - 1 do
         local right_col = row == self.node.start_row and self.data.marker.end_col - 1 or left_col
         self:padding_mark(row, left_col, self.bullet.left_pad)
         self:padding_mark(row, right_col, self.bullet.right_pad)
     end
 end
 
+---@private
+---@param root? render.md.Node
+---@return integer
+function Render:end_row(root)
+    local next_list = self.node:child('list')
+    if next_list ~= nil then
+        return next_list.start_row
+    end
+    local end_row = self.node.end_row
+    -- On the last item of the root list ignore the last line if it is empty
+    if root ~= nil and root.end_row == end_row then
+        if Str.width(self.node:line('last', 0)) == 0 then
+            return end_row - 1
+        end
+    end
+    return end_row
+end
+
 ---@private
 ---@param row integer
 ---@param col integer