feat(hosting,prospecting): add hosting unit tests and fix template bugs

- Add 55 unit tests for hosting module (hosted site service, client
  service service, stats service) with full fixture setup
- Fix table_empty_state macro: add x_message param for dynamic Alpine.js
  expressions rendered via x-text instead of server-side Jinja
- Fix hosting templates (sites, clients) using message= with Alpine
  expressions that rendered as literal text
- Fix prospecting templates (leads, scan-jobs, prospects) using
  nonexistent subtitle= param, migrated to x_message=
- Align hosting and prospecting admin templates with shared design system

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

app/templates/shared/macros/tables.html

@@ -222,15 +222,18 @@
     - message: Empty state message
     - show_condition: Alpine.js condition (default: 'true')
     - has_filters: Whether to show filter hint (default: true)
+    - x_message: Alpine.js expression for dynamic message (rendered via x-text)
 #}
-{% macro table_empty_state(colspan, icon='inbox', title='No data found', message='', show_condition='true', has_filters=true) %}
+{% macro table_empty_state(colspan, icon='inbox', title='No data found', message='', show_condition='true', has_filters=true, x_message='') %}
 <template x-if="{{ show_condition }}">
     <tr>
         <td colspan="{{ colspan }}" class="px-4 py-8 text-center text-gray-600 dark:text-gray-400">
             <div class="flex flex-col items-center">
                 <span x-html="$icon('{{ icon }}', 'w-12 h-12 mb-2 text-gray-300')"></span>
                 <p class="font-medium">{{ title }}</p>
-                {% if message %}
+                {% if x_message %}
+                <p class="text-xs mt-1" x-text="{{ x_message }}"></p>
+                {% elif message %}
                 <p class="text-xs mt-1">{{ message }}</p>
                 {% elif has_filters %}
                 <p class="text-xs mt-1">Try adjusting your search or filters</p>