add netrw preview scrolling

lua/netrw-preview.lua

@@ -626,6 +626,18 @@ local function schedule_leave_cleanup(state)
   end))
 end
 
+local function scroll_preview(direction, count)
+  local preview = find_preview_window(vim.api.nvim_get_current_tabpage())
+  if not preview then
+    return
+  end
+
+  local key = vim.keycode(direction > 0 and '<C-e>' or '<C-y>')
+  vim.api.nvim_win_call(preview, function()
+    vim.cmd.normal({ args = { tostring(count) .. key }, bang = true })
+  end)
+end
+
 function M.setup(buf)
   if vim.fn.has('nvim-0.12') == 0 or not is_valid_buffer(buf) then
     return false
@@ -653,6 +665,24 @@ function M.setup(buf)
     silent = true,
   })
 
+  vim.keymap.set('n', '<M-j>', function()
+    scroll_preview(1, vim.v.count1)
+  end, {
+    buffer = buf,
+    desc = 'Netrw: Scroll preview down',
+    nowait = true,
+    silent = true,
+  })
+
+  vim.keymap.set('n', '<M-k>', function()
+    scroll_preview(-1, vim.v.count1)
+  end, {
+    buffer = buf,
+    desc = 'Netrw: Scroll preview up',
+    nowait = true,
+    silent = true,
+  })
+
   vim.api.nvim_create_autocmd('CursorMoved', {
     group = preview_group,
     buffer = buf,