chore(lua/plugins): cleanup and reorganize plugin configurations, dropping deprecated plugins and introducing new folding, smoothing, and screenshot tools

New Features:
- Added ufo.nvim for advanced folding with Treesitter and indent providers
- Added neoscroll.nvim for smooth scrolling
- Added smartcolumn.nvim to enforce colorcolumn only when needed
- Added codesnap.nvim for markdown screenshot generation
- Added Markview toggle shortcut for markdown preview

Enhancements:
- Configured folding options (foldcolumn, foldlevel, provider selector)
- Added keybindings for opening/closing all folds and toggling fold visibility
- Updated plugin loading conditions and lazy loading patterns

Bug Fixes: — No bug fixes included in this change —

lua/plugins/syntax.lua

@@ -0,0 +1,78 @@
+return {
+
+    -- treesitter
+    {
+        'nvim-treesitter/nvim-treesitter',
+        build = ':TSUpdate',
+        event = { 'BufReadPost', 'BufNewFile' },
+        config = function()
+            require('nvim-treesitter.configs').setup({
+                ensure_installed = require('config.extensions').ts_parsers,
+                auto_install = true,
+                highlight = {
+                    enable = true,
+                    additional_vim_regex_highlighting = true,
+                },
+                indent = {
+                    enable = true,
+                },
+            })
+        end,
+    },
+
+    -- auto pairs
+    {
+        'windwp/nvim-autopairs',
+        event = 'InsertEnter',
+        config = function()
+            local npairs = require('nvim-autopairs')
+            local Rule = require('nvim-autopairs.rule')
+            local conds = require('nvim-autopairs.conds')
+
+            npairs.setup()
+
+            -- Autoclosing angle-brackets.
+            npairs.add_rule(Rule('<', '>', {
+                -- Avoid conflicts with nvim-ts-autotag.
+                '-html',
+                '-javascriptreact',
+                '-typescriptreact',
+            }):with_pair(conds.before_regex('%a+:?:?$', 3)):with_move(function(opts)
+                return opts.char == '>'
+            end))
+        end,
+    },
+
+    -- auto tag
+    {
+        'windwp/nvim-ts-autotag',
+        ft = {
+            'html',
+            'xml',
+            'javascript',
+            'typescript',
+            'javascriptreact',
+            'typescriptreact',
+            'jsx',
+            'tsx',
+            'vue',
+            'svelte',
+            'markdown',
+            'htmldjango',
+        },
+        event = 'InsertEnter',
+        lazy = true,
+        opts = {
+            -- Defaults
+            enable_close = true,           -- Auto close tags
+            enable_rename = true,          -- Auto rename pairs of tags
+            enable_close_on_slash = false, -- Auto close on trailing </
+        },
+    },
+
+    -- syntax highlight for mdx
+    {
+        'davidmh/mdx.nvim',
+        dependencies = { 'nvim-treesitter/nvim-treesitter' },
+    },
+}