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_snippet.md

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+---
+name: metabase_update_snippet
+kind: function
+lang: py
+domain: infra
+version: "1.0.0"
+purity: impure
+signature: "def metabase_update_snippet(client: MetabaseClient, snippet_id: int, **fields) -> dict"
+description: "Actualiza campos de un SQL snippet en Metabase. Acepta name, content, description, collection_id, archived via **fields."
+tags: [metabase, snippet, update, api, python]
+uses_functions: []
+uses_types: [MetabaseClient_go_infra]
+returns: []
+returns_optional: false
+error_type: "error_go_core"
+imports: [httpx]
+params:
+  - name: client
+    desc: "instancia autenticada de MetabaseClient"
+  - name: snippet_id
+    desc: "ID numerico del snippet a actualizar"
+  - name: "**fields"
+    desc: "campos a modificar: name (str), content (str), description (str), collection_id (int), archived (bool)"
+output: "dict: snippet actualizado con todos los campos incluyendo updated_at"
+tested: false
+tests: []
+test_file_path: ""
+file_path: "python/functions/metabase/snippets.py"
+---
+
+## Ejemplo
+
+```python
+# Actualizar solo el contenido SQL
+updated = metabase_update_snippet(
+    client, 42,
+    content="WITH supply_full AS (SELECT * FROM supply_orders)",
+    description="Version simplificada sin JOINs",
+)
+print(updated["updated_at"])
+
+# Renombrar
+metabase_update_snippet(client, 42, name="supply_orders_simple_cte")
+
+# Mover a otra coleccion
+metabase_update_snippet(client, 42, collection_id=7)
+
+# Archivar (o usar metabase_archive_snippet)
+metabase_update_snippet(client, 42, archived=True)
+```
+
+## Notas
+
+Solo los campos reconocidos (name, content, description, collection_id, archived) se incluyen en el body.
+Campos desconocidos en **fields se ignoran silenciosamente para evitar errores 400.
+Para archivar en una sola llamada, preferir metabase_archive_snippet.