Modularize bot: per-guild config system for roles/channels/categories

- Add utils/guild_config.py: centralized config loader per guild (data/guilds/{id}.json)
- Add commandes/config.py: /config set_role, /config set_channel, /config set_category, /config voir, /config reset
- Replace ALL hardcoded role IDs (banquier, gouvernement, citoyen, staff, ems, permis, fbm, ursaff, etc.) with guild_config lookups
- Replace ALL hardcoded channel IDs (welcome, candidature, questions, mp_reception) with guild_config lookups
- Replace ALL hardcoded category IDs (ticket) with guild_config lookups
- Remove duplicate commandes/welcome_message.py (kept utils/ version)
- Remove 20+ hardcoded snowflake IDs across 22 files
- Guilds configure via /config on Discord, no code changes needed

commandes/restranscription_staff.py

@@ -1,6 +1,7 @@
 import discord
 from discord.ext import commands
 from discord import app_commands
+from utils.guild_config import get_guild_channel
 
 class RestranscriptionStaff(commands.Cog):
     def __init__(self, bot):
@@ -18,7 +19,9 @@ class RestranscriptionStaff(commands.Cog):
 
         # Réceptionner les MPs
         if isinstance(message.channel, discord.DMChannel):
-            channel_reception = self.bot.get_channel(1277951933105049601)  # Remplacez par votre ID de salon
+            channel_reception = get_guild_channel(message.guild, "mp_reception")
+            if channel_reception is None:
+                return
 
             embed = discord.Embed(description=message.content,
                                   color=discord.Color.blue())