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/compte_banque_nationale.py

@@ -3,8 +3,7 @@ from discord import app_commands
 from discord.ext import commands
 import json
 import math
-
-BANQUE_NATIONALE_ROLE_ID = 1362031086959329470  # Remplace par l’ID réel du rôle banque_nationale
+from utils.guild_config import has_role
 
 class CompteBanqueNationale(commands.Cog):
     def __init__(self, bot):
@@ -41,7 +40,7 @@ class CompteBanqueNationale(commands.Cog):
 
     @app_commands.command(name="voir_banque_nationale", description="Voir solde et transactions du compte banque nationale")
     async def voir_banque_nationale(self, interaction: discord.Interaction):
-        if not any(role.id == BANQUE_NATIONALE_ROLE_ID for role in interaction.user.roles):
+        if not has_role(interaction.user, "banque_nationale"):
             await interaction.response.send_message("❌ Vous n'avez pas la permission d'accéder à ce compte.", ephemeral=True)
             return