fix: bot text confirmation on relay + rename @bridge to @gravity + channel dedup

bot.py

@@ -475,6 +475,11 @@ class GravityBot(commands.Bot):
         if text:
             self.bridge.write_command(project, text, project_name=project)
             await message.add_reaction("📨")
+            embed = discord.Embed(
+                description=f"📨 → **{project}** IDE에 전달됨\n`{text[:100]}`",
+                color=discord.Color.blurple(),
+            )
+            await message.channel.send(embed=embed, delete_after=10)
 
         await self.process_commands(message)