feat: add 802.1X switch access policy support

- Add meraki_switch_access_policy resource to module (multi-auth, critical VLAN)
- Add meraki_switch_port resource for per-port policy assignment
- Add switch_access_policies and switch_port_configs variables to module and site
- Create switch.auto.tfvars for BCN01-LAB with 802.1X-CORPO policy
  (RADIUS: 15.15.15.15:1912, critical VLAN: 100, host_mode: Multi-Auth)
- switch_port_configs starts empty; add serial + port_id to assign policy to ports

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

sites/BCN01-LAB/switch.auto.tfvars

@@ -0,0 +1,45 @@
+# Configuración de switches MS - BCN01-LAB
+# El shared secret de RADIUS se pasa via TF_VAR_radius_secret (GitHub secret: RADIUS_SECRET)
+
+# --- POLÍTICAS DE ACCESO 802.1X ---
+switch_access_policies = [
+  {
+    name                               = "802.1X-CORPO"
+    access_policy_type                 = "802.1x"
+    host_mode                          = "Multi-Auth"
+    radius_accounting_enabled          = false
+    radius_re_authentication_interval  = 0
+    url_redirect_walled_garden_enabled = false
+
+    # VLAN a la que cae el puerto si el RADIUS no responde
+    # Cambiar por la VLAN deseada (ej. VLAN 100 = ACCESS)
+    radius_failed_auth_vlan_id = 100
+
+    radius_servers = [
+      {
+        host = "15.15.15.15"
+        port = 1912
+      }
+    ]
+  }
+]
+
+# --- PUERTOS DE SWITCH CON 802.1X ---
+# Para configurar puertos, añade entradas con el serial del switch y el port_id.
+# El serial aparece en Dashboard > Switches > nombre del switch > Overview.
+# access_policy_number: número auto-asignado por Meraki a la política creada arriba
+#   (visible en Dashboard > Switches > Switch settings > Access policies, o en el output de terraform)
+#
+# Ejemplo:
+# switch_port_configs = [
+#   {
+#     serial               = "XXXX-XXXX-XXXX"  # serial del switch
+#     port_id              = "1"
+#     name                 = "Workstation 1"
+#     type                 = "access"
+#     vlan                 = 100
+#     access_policy_type   = "Custom access policy"
+#     access_policy_number = 1  # número de la política 802.1X-CORPO
+#   },
+# ]
+switch_port_configs = []