feat: add welcomer cog for greeting new members

Introduces a simple cog that welcomes new users via customizable messages in designated channels, enhancing community engagement.

Handles channel selection with fallbacks and includes error resilience for permission issues.

welcomer/welcomer.py

@@ -0,0 +1,40 @@
+# welcomer.py
+
+from redbot.core import commands
+from redbot.core.bot import Red
+import discord
+
+class Welcomer(commands.Cog):
+    """A simple cog to welcome new users."""
+
+    def __init__(self, bot: Red):
+        self.bot = bot
+
+    @commands.Cog.listener()
+    async def on_member_join(self, member):
+        """Greets a new member when they join the server."""
+        
+        guild = member.guild
+        while True:
+            # Try to find a channel named 'welcome'
+            channel = discord.utils.get(guild.text_channels, name='welcome')
+            if channel is None:
+                # If not found, try to find a channel named 'general'
+                channel = discord.utils.get(guild.text_channels, name='general')
+            if channel is None:
+                # If still not found, use the first text channel available
+                if guild.text_channels:
+                    channel = guild.text_channels[0]
+                else:
+                    # If no text channels exist, exit the function
+                    return
+            try:
+                await channel.send(f"Welcome to the server, {member.mention}!")
+                break  # Exit the loop after successfully sending the message
+            except discord.Forbidden:
+                # If we don't have permission to send messages in this channel, try again
+                continue
+
+# This function allows Red to load the cog
+async def setup(bot: Red):
+    await bot.add_cog(Welcomer(bot))