feat(hosting): add industry template infrastructure (Workstream 3B)

5 industry templates as JSON presets, each with theme + multi-page content:
- generic: clean minimal (homepage, about, contact)
- restaurant: warm tones, Playfair Display (homepage, about, menu, contact)
- construction: amber/earth tones, Montserrat (homepage, services, projects, contact)
- auto-parts: red/bold, parts-focused (homepage, catalog, contact)
- professional-services: navy/blue, Merriweather (homepage, services, team, contact)

Each template has:
- meta.json (name, description, tags, languages)
- theme.json (colors, fonts, layout, header style)
- pages/*.json (section-based homepage + content pages with i18n)
- {{placeholder}} variables for prospect data injection

TemplateService loads from templates_library/ directory with caching.
GET /admin/hosting/sites/templates endpoint to list available templates.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/hosting/templates_library/generic/pages/homepage.json

@@ -0,0 +1,35 @@
+{
+  "slug": "homepage",
+  "title": "{{business_name}}",
+  "template": "full",
+  "is_published": true,
+  "show_in_header": false,
+  "sections": {
+    "hero": {
+      "enabled": true,
+      "title": {"translations": {"en": "{{business_name}}", "fr": "{{business_name}}"}},
+      "subtitle": {"translations": {"en": "{{meta_description}}", "fr": "{{meta_description}}"}},
+      "background_type": "gradient",
+      "buttons": [
+        {"label": {"translations": {"en": "Contact Us", "fr": "Contactez-nous"}}, "url": "/contact", "style": "primary"}
+      ]
+    },
+    "features": {
+      "enabled": true,
+      "title": {"translations": {"en": "What We Offer", "fr": "Nos Services"}},
+      "items": [
+        {"icon": "shield-check", "title": {"translations": {"en": "Quality", "fr": "Qualité"}}, "description": {"translations": {"en": "Committed to excellence in everything we do", "fr": "Engagés pour l'excellence dans tout ce que nous faisons"}}},
+        {"icon": "clock", "title": {"translations": {"en": "Reliability", "fr": "Fiabilité"}}, "description": {"translations": {"en": "Dependable service you can count on", "fr": "Un service fiable sur lequel vous pouvez compter"}}},
+        {"icon": "users", "title": {"translations": {"en": "Experience", "fr": "Expérience"}}, "description": {"translations": {"en": "Years of expertise at your service", "fr": "Des années d'expertise à votre service"}}}
+      ]
+    },
+    "cta": {
+      "enabled": true,
+      "title": {"translations": {"en": "Ready to get started?", "fr": "Prêt à commencer ?"}},
+      "subtitle": {"translations": {"en": "Contact us today for a free consultation", "fr": "Contactez-nous pour une consultation gratuite"}},
+      "buttons": [
+        {"label": {"translations": {"en": "Get in Touch", "fr": "Nous Contacter"}}, "url": "/contact", "style": "primary"}
+      ]
+    }
+  }
+}