fix: resolve styles & presets in overrides

## Details

After changing how styles are handled I neglected to handle values
placed inside of overrides. This meant that they would effectively be
ignored as they do not modify the concrete values. To fix this loop over
overrides and resolve them as part of the logic of the `presets` module.

Author: MeanderingProgrammer

doc/render-markdown.txt

@@ -1,4 +1,4 @@
-*render-markdown.txt*        For NVIM v0.11.3        Last change: 2025 July 28
+*render-markdown.txt*        For NVIM v0.11.3        Last change: 2025 July 31
 
 ==============================================================================
 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 = '8.6.9'
+M.version = '8.6.10'
 
 function M.check()
     M.start('version')

lua/render-markdown/lib/presets.lua

@@ -11,11 +11,12 @@ local M = {}
 ---@param user render.md.UserConfig
 ---@return render.md.UserConfig
 function M.get(user)
-    return vim.tbl_deep_extend('force', M.config(user), {
-        code = M.code(user),
-        pipe_table = M.pipe_table(user),
-        win_options = M.win_options(user),
-    })
+    return vim.tbl_deep_extend(
+        'force',
+        M.config(user),
+        M.partial(user),
+        M.overrides(user)
+    )
 end
 
 ---@private
@@ -45,8 +46,41 @@ function M.config(user)
     return presets[user.preset] or {}
 end
 
+---@private
+---@param user render.md.partial.UserConfig
+---@return render.md.partial.UserConfig
+function M.partial(user)
+    ---@type render.md.partial.UserConfig
+    return {
+        code = M.code(user),
+        pipe_table = M.pipe_table(user),
+        win_options = M.win_options(user),
+    }
+end
+
 ---@private
 ---@param user render.md.UserConfig
+---@return render.md.UserConfig
+function M.overrides(user)
+    local configs = {} ---@type render.md.overrides.UserConfig
+    for _, name in ipairs({ 'buflisted', 'buftype', 'filetype' }) do
+        local overrides = (user.overrides or {})[name] ---@type table<any, render.md.partial.UserConfig>?
+        if type(overrides) == 'table' then
+            local config = {} ---@type table<any, render.md.partial.UserConfig>
+            for value, override in pairs(overrides) do
+                if type(override) == 'table' then
+                    config[value] = M.partial(override)
+                end
+            end
+            configs[name] = config
+        end
+    end
+    ---@type render.md.UserConfig
+    return { overrides = configs }
+end
+
+---@private
+---@param user render.md.partial.UserConfig
 ---@return render.md.code.UserConfig
 function M.code(user)
     ---@type table<render.md.code.Style?, render.md.code.UserConfig?>
@@ -59,7 +93,7 @@ function M.code(user)
 end
 
 ---@private
----@param user render.md.UserConfig
+---@param user render.md.partial.UserConfig
 ---@return render.md.table.UserConfig
 function M.pipe_table(user)
     ---@type table<render.md.table.Preset?, render.md.table.UserConfig?>
@@ -104,7 +138,7 @@ function M.pipe_table(user)
 end
 
 ---@private
----@param user render.md.UserConfig
+---@param user render.md.partial.UserConfig
 ---@return render.md.window.UserConfigs
 function M.win_options(user)
     ---@type table<boolean?, render.md.window.UserConfigs?>

tests/presets_spec.lua

@@ -0,0 +1,59 @@
+---@module 'luassert'
+
+---@param user render.md.UserConfig
+---@param expected render.md.UserConfig
+local function validate(user, expected)
+    local actual = require('render-markdown.lib.presets').get(user)
+    assert.same(expected, actual)
+end
+
+describe('presets', function()
+    it('overlap', function()
+        validate({
+            preset = 'lazy',
+            code = { style = 'normal' },
+        }, {
+            file_types = { 'markdown', 'norg', 'rmd', 'org', 'codecompanion' },
+            code = {
+                sign = false,
+                width = 'block',
+                right_pad = 1,
+                language = false,
+            },
+            heading = {
+                sign = false,
+                icons = {},
+            },
+            checkbox = { enabled = false },
+            pipe_table = {},
+            win_options = {},
+            overrides = {},
+        })
+    end)
+
+    it('override', function()
+        validate({
+            code = { style = 'none' },
+            overrides = {
+                buftype = {
+                    nofile = {
+                        code = { style = 'normal' },
+                    },
+                },
+            },
+        }, {
+            code = { enabled = false },
+            pipe_table = {},
+            win_options = {},
+            overrides = {
+                buftype = {
+                    nofile = {
+                        code = { language = false },
+                        pipe_table = {},
+                        win_options = {},
+                    },
+                },
+            },
+        })
+    end)
+end)