feat: Añadir sistema de mensajes de bienvenida con traducción para Discord

- Nueva tabla 'welcome_messages' en la base de datos
- Panel web con página de configuración de bienvenida (/welcome)
  - Listar, crear, editar y eliminar mensajes por servidor
  - Vista previa del mensaje
  - Plantillas predefinidas
- Bot Discord:
  - Nuevo intent 'members' para detectar nuevos usuarios
  - Evento on_member_join que envía mensaje de bienvenida
  - Botones de traducción en mensajes de bienvenida
- Actualizada configuración de MySQL en docker-compose.yml
- Añadido logging de debug para traducciones

botdiscord/ui.py

@@ -8,7 +8,8 @@ from botdiscord.database import (
     get_cached_translation, 
     get_active_languages, 
     get_bot_languages,
-    get_available_languages # Importante: esta función trae los datos del panel web
+    get_available_languages,
+    save_message
 )
 
 class TranslationButton(discord.ui.Button):
@@ -109,3 +110,71 @@ class ConfigView(discord.ui.View):
     def __init__(self, guild_id: int, bot_type: str = "discord"):
         super().__init__()
         self.add_item(ConfigSelect(guild_id, bot_type))
+
+class WelcomeTranslationButton(discord.ui.Button):
+    def __init__(self, lang_name: str, lang_code: str, flag: str):
+        label = flag if flag else lang_name
+        custom_id = f"btn_welcome_{lang_code}"
+        super().__init__(label=label, style=discord.ButtonStyle.primary, custom_id=custom_id)
+        self.lang_code = lang_code
+        self.lang_name = lang_name
+        self.flag = flag
+
+    async def callback(self, interaction: discord.Interaction):
+        await interaction.response.defer()
+        
+        try:
+            original_msg_id = interaction.message.id
+            db_msg = get_message(original_msg_id)
+            
+            if not db_msg:
+                await interaction.followup.send("⚠️ Mensaje no encontrado en la base de datos.", ephemeral=True)
+                return
+
+            text = db_msg['content']
+            mentions_map = db_msg['mentions_map'] or {}
+            
+            cached = get_cached_translation(original_msg_id, self.lang_code)
+            if cached:
+                translated = cached
+            else:
+                translated = await translate_text(text, self.lang_code)
+                save_translation(original_msg_id, self.lang_code, translated)
+            
+            translated = html.unescape(translated)
+            if mentions_map:
+                for placeholder, mention in mentions_map.items():
+                    translated = translated.replace(placeholder, mention)
+                    translated = translated.replace(placeholder.replace(" ", ""), mention)
+            
+            guild_id = interaction.guild_id
+            active_codes = get_active_languages(guild_id)
+            if not active_codes:
+                active_codes = get_bot_languages("discord")
+            
+            db_langs = get_available_languages()
+            
+            new_view = discord.ui.View(timeout=None)
+            for lang in db_langs:
+                if lang['code'] in active_codes:
+                    new_view.add_item(WelcomeTranslationButton(lang['name'], lang['code'], lang.get('flag', '')))
+            
+            await interaction.edit_original_response(content=translated, view=new_view)
+            
+        except Exception as e:
+            import traceback
+            print(f"[ERROR Welcome UI] {e}")
+            traceback.print_exc()
+            await interaction.followup.send(f"❌ Error: {str(e)}", ephemeral=True)
+
+class WelcomeTranslationView(discord.ui.View):
+    def __init__(self, guild_id: int):
+        super().__init__(timeout=None)
+        active_codes = get_active_languages(guild_id)
+        if not active_codes:
+            active_codes = get_bot_languages("discord")
+        
+        db_langs = get_available_languages()
+        for lang in db_langs:
+            if lang['code'] in active_codes:
+                self.add_item(WelcomeTranslationButton(lang['name'], lang['code'], lang.get('flag', '')))