Feat: support format on save

- use conform to format file

lua/custom/plugins/conform.lua

@@ -0,0 +1,20 @@
+return {
+  'stevearc/conform.nvim',
+  event = { 'BufReadPre', 'BufNewFile' },
+  opts = {
+    formatters_by_ft = {
+      lua = { 'stylua' },
+      python = function(bufnr)
+        if require('conform').get_formatter_info('ruff_format', bufnr).available then
+          return { 'ruff_format' }
+        else
+          return { 'isort', 'black' }
+        end
+      end,
+    },
+    format_on_save = {
+      timeout_ms = 500,
+      lsp_fallback = true,
+    },
+  },
+}