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_create_snippet.md

@@ -0,0 +1,70 @@
+---
+name: metabase_create_snippet
+kind: function
+lang: py
+domain: infra
+version: "1.0.0"
+purity: impure
+signature: "def metabase_create_snippet(client: MetabaseClient, name: str, content: str, description: str = \"\", collection_id: int = 0) -> dict"
+description: "Crea un nuevo SQL snippet reutilizable en Metabase. El snippet se referencia en queries nativas con {{snippet: nombre}}."
+tags: [metabase, snippet, create, 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: name
+    desc: "nombre del snippet; se usa en queries con la sintaxis {{snippet: nombre}}"
+  - name: content
+    desc: "SQL del snippet: puede ser una CTE completa, subquery o cualquier fragmento SQL reutilizable"
+  - name: description
+    desc: "descripcion opcional del proposito del snippet"
+  - name: collection_id
+    desc: "ID de la coleccion donde guardar el snippet; 0 para la raiz (Our analytics)"
+output: "dict: snippet creado con id asignado por Metabase, name, content, description, collection_id, created_at"
+tested: false
+tests: []
+test_file_path: ""
+file_path: "python/functions/metabase/snippets.py"
+---
+
+## Ejemplo
+
+```python
+# Crear snippet con CTE reutilizable
+snippet = metabase_create_snippet(
+    client,
+    "supply_orders_cte",
+    """
+WITH supply_full AS (
+    SELECT so.id, so.service_request_id,
+           sr.channel_id, ch.name AS channel_name
+    FROM supply_orders so
+    LEFT JOIN service_requests sr ON so.service_request_id = sr.id
+    LEFT JOIN channels ch ON sr.channel_id = ch.id
+)
+""",
+    description="CTE base de supply_orders con 6 JOINs para cruce con NAV",
+)
+print(snippet["id"], snippet["name"])
+
+# Usar el snippet en una card
+from metabase.cards import metabase_create_card
+card = metabase_create_card(client, "Revenue", {
+    "database": 6,
+    "type": "native",
+    "native": {
+        "query": "{{snippet: supply_orders_cte}} SELECT channel_name, COUNT(*) FROM supply_full GROUP BY 1"
+    }
+})
+```
+
+## Notas
+
+El campo `name` debe ser unico en Metabase — el servidor retorna 400 si ya existe un snippet con ese nombre.
+Si `collection_id` es 0 o no se provee, el snippet se guarda en la raiz.
+Solo se envian al body los campos no vacios/cero para evitar conflictos con defaults del servidor.