feat: reduce height of LSP hover doc window based on concealed lines

## Details

Request: #384

Since the `conceal_lines` directive is enabled in the default highlights
neovim actively handles reducing the height of LSP hover doc windows to
remove unnecessary vertical space.

This happens here:

https://github.com/neovim/neovim/blob/master/runtime/lua/vim/lsp/util.lua#L1657-L1661

```lua
-- Reduce window height if TS highlighter conceals code block backticks.
local conceal_height = api.nvim_win_text_height(floating_winnr, {}).all
if conceal_height < api.nvim_win_get_height(floating_winnr) then
    api.nvim_win_set_height(floating_winnr, conceal_height)
end
```

Since our decorations are added separately from highlights and behave
very differently there would be no way for neovim to practically pickup
highlights added by this plugin.

To get around this we essentially re-implement this same logic as part
of this plugin. After the first load of a buffer when we are just about
to add our `extmark`s check if the buffer is related to LSP hover docs
and if it is adjust the height taking into account the concealed lines
that will be added (removed) by this plugin.

I don't see this as a bug, since adjusting windows to fit their content
is not something this plugin ever intended to do and supporting every
feature in neovim is not the goal. However, since this is for a very
specific scenario and the implementation is straightforward I've added
it.

> [!CAUTION]
> We'll likely need to update how we identify LSP hover doc buffers over
> time since the current approach is tied to internal undocumented behavior.

> [!NOTE]
> See if we can add a marker on LSP buffers that is a documented feature
> others can rely on, if such a thing doesn't already exist.

Author: MeanderingProgrammer

README.md

@@ -236,7 +236,7 @@ require('render-markdown').setup({
         -- Which elements to always show, ignoring anti conceal behavior. Values can either be
         -- booleans to fix the behavior or string lists representing modes where anti conceal
         -- behavior will be ignored. Valid values are:
-        --   head_icon, head_background, head_border, code_language, code_background, code_border
+        --   head_icon, head_background, head_border, code_language, code_background, code_border,
         --   dash, bullet, check_icon, check_scope, quote, table_border, callout, link, sign
         ignore = {
             code_background = true,

doc/render-markdown.txt

@@ -301,7 +301,7 @@ Default Configuration ~
             -- Which elements to always show, ignoring anti conceal behavior. Values can either be
             -- booleans to fix the behavior or string lists representing modes where anti conceal
             -- behavior will be ignored. Valid values are:
-            --   head_icon, head_background, head_border, code_language, code_background, code_border
+            --   head_icon, head_background, head_border, code_language, code_background, code_border,
             --   dash, bullet, check_icon, check_scope, quote, table_border, callout, link, sign
             ignore = {
                 code_background = true,

lua/render-markdown/core/ui.lua

@@ -1,4 +1,5 @@
 local Buffer = require('render-markdown.core.buffer')
+local Compat = require('render-markdown.lib.compat')
 local Context = require('render-markdown.core.context')
 local Env = require('render-markdown.lib.env')
 local Extmark = require('render-markdown.core.extmark')
@@ -144,6 +145,9 @@ function M.run_update(buf, win, change)
         end
         local hidden = config:hidden(mode, row)
         local extmarks = buffer:get_marks()
+        if initial then
+            Compat.lsp_window_height(win, extmarks)
+        end
         for _, extmark in ipairs(extmarks) do
             if extmark:get().conceal and extmark:inside(hidden) then
                 extmark:hide(M.ns, buf)

lua/render-markdown/health.lua

@@ -5,7 +5,7 @@ local state = require('render-markdown.state')
 local M = {}
 
 ---@private
-M.version = '8.1.24'
+M.version = '8.1.25'
 
 function M.check()
     M.start('version')

lua/render-markdown/init.lua

@@ -417,7 +417,7 @@ M.default_config = {
         -- Which elements to always show, ignoring anti conceal behavior. Values can either be
         -- booleans to fix the behavior or string lists representing modes where anti conceal
         -- behavior will be ignored. Valid values are:
-        --   head_icon, head_background, head_border, code_language, code_background, code_border
+        --   head_icon, head_background, head_border, code_language, code_background, code_border,
         --   dash, bullet, check_icon, check_scope, quote, table_border, callout, link, sign
         ignore = {
             code_background = true,

lua/render-markdown/integ/source.lua

@@ -29,7 +29,7 @@ end
 ---@return lsp.CompletionItem[]?
 function M.items(buf, row, col)
     buf = buf == 0 and Env.buf.current() or buf
-    local node = M.node(buf, row, col)
+    local node = M.node(buf, row, col, 'markdown')
     if node == nil or node:range() ~= row then
         return nil
     end
@@ -72,19 +72,20 @@ end
 ---@param buf integer
 ---@param row integer
 ---@param col integer
+---@param lang string
 ---@return TSNode?
-function M.node(buf, row, col)
+function M.node(buf, row, col, lang)
     -- Parse current row to get up to date node
-    local has_parser, parser = pcall(vim.treesitter.get_parser, buf)
+    local has_parser, parser = pcall(vim.treesitter.get_parser, buf, lang)
     if not has_parser or parser == nil then
         return nil
     end
     parser:parse({ row, row })
 
     local node = vim.treesitter.get_node({
         bufnr = buf,
-        lang = 'markdown',
         pos = { row, col },
+        lang = lang,
     })
     if node ~= nil and node:type() == 'paragraph' then
         node = node:prev_sibling()

lua/render-markdown/lib/compat.lua

@@ -0,0 +1,29 @@
+---@class render.md.Compat
+local M = {}
+
+---@param win integer
+---@param extmarks render.md.Extmark[]
+---@see vim.lsp.util.open_floating_preview
+function M.lsp_window_height(win, extmarks)
+    -- This is a fragile way of identifying whether this is a floating LSP buffer,
+    -- comes from the implementation and not from any documentation
+    local lsp_buf = pcall(vim.api.nvim_win_get_var, win, 'lsp_floating_bufnr')
+    if not lsp_buf then
+        return
+    end
+    local concealed = 0
+    for _, extmark in ipairs(extmarks) do
+        if extmark:get().opts.conceal_lines ~= nil then
+            concealed = concealed + 1
+        end
+    end
+    if concealed == 0 then
+        return
+    end
+    local height = vim.api.nvim_win_text_height(win, {}).all - concealed
+    if height < vim.api.nvim_win_get_height(win) then
+        vim.api.nvim_win_set_height(win, height)
+    end
+end
+
+return M