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/modules/hosting/routes/api/admin.py

@@ -14,7 +14,7 @@ from .admin_services import router as admin_services_router
 from .admin_sites import router as admin_sites_router
 from .admin_stats import router as admin_stats_router
 
-router = APIRouter()
+router = APIRouter(prefix="/hosting")
 
 router.include_router(admin_sites_router, tags=["hosting-sites"])
 router.include_router(admin_services_router, tags=["hosting-services"])