refactor: restructure core modules into config directory for better organization

lua/plugins/formatting.lua

@@ -0,0 +1,64 @@
+return {
+    "stevearc/conform.nvim",
+    dependencies = { "zapling/mason-conform.nvim" },
+    event = "BufWritePre",
+    cmd = "ConformInfo",
+    keys = { "<leader>tf" },
+    config = function()
+        require("conform").setup({
+            formatters = {
+                ["markdown-toc"] = {
+                    condition = function(_, ctx)
+                        for _, line in ipairs(vim.api.nvim_buf_get_lines(ctx.buf, 0, -1, false)) do
+                            if line:find("<!%-%-% toc %-%->") then
+                                return true
+                            end
+                        end
+                    end,
+                },
+                ["markdownlint-cli2"] = {
+                    condition = function(_, ctx)
+                        local diag = vim.tbl_filter(function(d)
+                            return d.source == "markdownlint"
+                        end, vim.diagnostic.get(ctx.buf))
+                        return #diag > 0
+                    end,
+                },
+            },
+            formatters_by_ft = {
+                ["lua"] = { "stylua" },
+                ["c"] = { "clang_format" },
+                ["cpp"] = { "clang_format" },
+                ["h"] = { "clang_format" },
+                ["python"] = { "ruff_fix", "ruff_format", "ruff_organize_imports" },
+                ["javascript"] = { "biome" },
+                ["typescript"] = { "biome" },
+                ["typescriptreact"] = { "biome" },
+                ["markdown"] = { "prettier", "markdownlint-cli2", "markdown-toc" },
+                ["markdown.mdx"] = { "prettier", "markdownlint-cli2", "markdown-toc" },
+                ["mdx"] = { "prettier" },
+                ["_"] = { "trim_whitespace" },
+            },
+            options = {
+                stop_after_first = true,
+            },
+            format_after_save = function(bufnr)
+                if not vim.b[bufnr].conform_disable then
+                    return {
+                        lsp_format = "fallback",
+                    }
+                end
+            end,
+        })
+
+        vim.keymap.set("n", "<leader>tf", function()
+            vim.b.conform_disable = not vim.b.conform_disable
+            local status = vim.b.conform_disable and "disabled" or "enabled"
+            vim.notify("Autoformat " .. status, vim.log.levels.INFO)
+        end, { desc = "Toggle autoformat" })
+        require("mason-conform").setup({
+            ensure_installed = require("config.extensions").formatter,
+            automatic_installation = true,
+        })
+    end,
+}