feat: add demo video to README and remove verbose at-mention feedback

Change-Id: Iaf8d4f2f812c9ee0e02c79b9820969251770376e
Signed-off-by: Thomas Kosiewski <tk@coder.com>

Author: ThomasK33

README.md

@@ -6,6 +6,8 @@
 
 A Neovim plugin that integrates with Claude Code CLI to provide a seamless AI coding experience in Neovim.
 
+https://github.com/user-attachments/assets/c625d855-5f32-4a1f-8757-1a3150e2786d
+
 ## Features
 
 - 🔄 **Pure Neovim WebSocket Server** (implemented with Neovim built-ins)

lua/claudecode/selection.lua

@@ -602,13 +602,7 @@ function M.send_at_mention_for_visual_selection()
   -- It refers to the server instance from lua/claudecode/server/init.lua
   local success = M.server.broadcast("at_mentioned", params)
 
-  if success then
-    vim.api.nvim_echo(
-      { { "At-mention sent to Claude for " .. vim.fn.fnamemodify(params.filePath, ":t"), "Normal" } },
-      false,
-      {}
-    )
-  else
+  if not success then
     vim.api.nvim_err_writeln("Failed to send at-mention.")
   end
 end