feat(metabase): nuevos modulos — snippets, notifications, dashboard_filters

Tres modulos nuevos con funciones CRUD completas:
- snippets: list, get, create, update, archive (SQL reutilizable)
- notifications: list, create_card_alert, create_dashboard_subscription, update, delete
- dashboard_filters: add_dashboard_filter (parameter_mappings sobre cards existentes)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

python/functions/metabase/metabase_update_notification.md

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+---
+name: metabase_update_notification
+kind: function
+lang: py
+domain: infra
+version: "1.0.0"
+purity: impure
+signature: "def metabase_update_notification(client: MetabaseClient, notification_id: int, **fields) -> dict"
+description: "Actualiza una notificacion existente de Metabase (alerta o suscripcion). Permite modificar active, handlers, subscriptions o payload. Endpoint: PUT /api/notification/:id."
+tags: [metabase, notification, update, api, python]
+uses_functions: []
+uses_types: []
+returns: []
+returns_optional: false
+error_type: "error_go_core"
+imports: []
+params:
+  - name: client
+    desc: "instancia autenticada de MetabaseClient"
+  - name: notification_id
+    desc: "ID de la notificacion a modificar"
+  - name: "**fields"
+    desc: "campos a actualizar: active (bool), handlers (list[dict]), subscriptions (list[dict]), payload (dict)"
+output: "dict: notificacion actualizada con id, active, payload_type, payload, subscriptions, handlers, updated_at"
+tested: false
+tests: []
+test_file_path: ""
+file_path: "python/functions/metabase/notifications.py"
+---
+
+## Ejemplo
+
+```python
+# Desactivar una alerta
+updated = metabase_update_notification(client, 99, active=False)
+print(updated["active"])  # False
+
+# Cambiar destinatarios
+updated = metabase_update_notification(
+    client,
+    99,
+    handlers=[{
+        "channel_type": "channel/email",
+        "recipients": [
+            {"type": "notification-recipient/user", "user_id": 2},
+        ],
+    }],
+)
+
+# Cambiar cron a diario a las 7am
+updated = metabase_update_notification(
+    client,
+    99,
+    subscriptions=[{
+        "type": "notification-subscription/cron",
+        "cron_schedule": "0 7 * * *",
+    }],
+)
+```
+
+## Notas
+
+Solo se envian los campos que se pasan como kwargs.
+Para reactivar una alerta previamente desactivada usar active=True.