feat: configurable indent extmark priority

## Details

Allows `indent.priority` to be configured which determines the priority
value used for indent extmarks. Default value is set to 0, which is the
value that was previously hard coded. This means no changes should occur
out of the box for users, but allows users to modify the value to work
better with their configuration.

Author: MeanderingProgrammer

README.md

@@ -812,6 +812,8 @@ require('render-markdown').setup({
         skip_heading = false,
         -- Prefix added when indenting, one per level.
         icon = '▎',
+        -- Priority to assign to extmarks.
+        priority = 0,
         -- Applied to icon.
         highlight = 'RenderMarkdownIndent',
     },
@@ -1543,6 +1545,8 @@ require('render-markdown').setup({
         skip_heading = false,
         -- Prefix added when indenting, one per level.
         icon = '▎',
+        -- Priority to assign to extmarks.
+        priority = 0,
         -- Applied to icon.
         highlight = 'RenderMarkdownIndent',
     },

doc/render-markdown.txt

@@ -1,4 +1,4 @@
-*render-markdown.txt*        For NVIM v0.11.2        Last change: 2025 July 09
+*render-markdown.txt*        For NVIM v0.11.2        Last change: 2025 July 14
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*
@@ -878,6 +878,8 @@ Default Configuration ~
             skip_heading = false,
             -- Prefix added when indenting, one per level.
             icon = '▎',
+            -- Priority to assign to extmarks.
+            priority = 0,
             -- Applied to icon.
             highlight = 'RenderMarkdownIndent',
         },
@@ -1585,6 +1587,8 @@ Indent Configuration ~
             skip_heading = false,
             -- Prefix added when indenting, one per level.
             icon = '▎',
+            -- Priority to assign to extmarks.
+            priority = 0,
             -- Applied to icon.
             highlight = 'RenderMarkdownIndent',
         },

lua/render-markdown/config/indent.lua

@@ -3,6 +3,7 @@
 ---@field skip_level integer
 ---@field skip_heading boolean
 ---@field icon string
+---@field priority integer
 ---@field highlight string
 
 ---@class render.md.indent.Cfg
@@ -26,6 +27,8 @@ M.default = {
     skip_heading = false,
     -- Prefix added when indenting, one per level.
     icon = '▎',
+    -- Priority to assign to extmarks.
+    priority = 0,
     -- Applied to icon.
     highlight = 'RenderMarkdownIndent',
 }
@@ -37,6 +40,7 @@ function M.validate(spec)
     spec:type('skip_level', 'number')
     spec:type('skip_heading', 'boolean')
     spec:type('icon', 'string')
+    spec:type('priority', 'number')
     spec:type('highlight', 'string')
     spec:check()
 end

lua/render-markdown/health.lua

@@ -5,7 +5,7 @@ local state = require('render-markdown.state')
 local M = {}
 
 ---@private
-M.version = '8.6.0'
+M.version = '8.6.1'
 
 function M.check()
     M.start('version')

lua/render-markdown/render/markdown/section.lua

@@ -38,7 +38,7 @@ function Render:run()
     local line = self:indent():line(false, self.data.level_change):get()
     for row = start_row, end_row do
         self.marks:add(false, row, 0, {
-            priority = 0,
+            priority = self.config.priority,
             virt_text = line,
             virt_text_pos = 'inline',
         })

lua/render-markdown/types.lua

@@ -174,6 +174,7 @@
 ---@field skip_level? integer
 ---@field skip_heading? boolean
 ---@field icon? string
+---@field priority? integer
 ---@field highlight? string
 
 ---@alias render.md.injection.UserConfigs table<string, render.md.injection.UserConfig>