Fix lingering erblint failures in sms_settings/index.html.erb

The previous lint fix swapped a `<% ... %>` block-opener style but
left a multi-line hash literal and multi-line `case` expression inside
the same ERB tag, which tripped Layout/FirstHashElementIndentation,
Layout/IndentationConsistency, and the closing-newline-before-`%>`
rule.

Reshape: each assignment lives in its own single-line `<% %>` tag, and
the per-provider sending-number lookup is a plain hash dispatch rather
than a multi-line case. Same runtime behaviour; lint-clean.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/views/sms_settings/index.html.erb

@@ -5,20 +5,10 @@
 
     <% value = @encrypted_config.value || {} %>
     <% sms_live = Sms.enabled_for?(current_account) %>
-    <% provider_labels = {
-        'bulkvs' => 'BulkVS',
-        'twilio' => 'Twilio',
-        'voipms' => 'VoIP.ms',
-        'signalwire' => 'SignalWire'
-      }
-      sending_number = case value['provider'].to_s
-                       when 'twilio'     then value['twilio_from']
-                       when 'voipms'     then value['voipms_did']
-                       when 'signalwire' then value['signalwire_from']
-                       else value['from_number']
-                       end
-      selected_provider = value['provider'].presence || 'bulkvs'
-    %>
+    <% provider_labels = { 'bulkvs' => 'BulkVS', 'twilio' => 'Twilio', 'voipms' => 'VoIP.ms', 'signalwire' => 'SignalWire' } %>
+    <% sending_number_keys = { 'twilio' => 'twilio_from', 'voipms' => 'voipms_did', 'signalwire' => 'signalwire_from' } %>
+    <% sending_number = value[sending_number_keys[value['provider'].to_s] || 'from_number'] %>
+    <% selected_provider = value['provider'].presence || 'bulkvs' %>
 
     <% if sms_live %>
       <div class="alert alert-success mb-4">