fix(loyalty): pass merchant name server-side to admin on-behalf headers

Load merchant name in page route handlers and pass to template context.
Headers now render as "Cards: Fashion Group S.A." using server-side
Jinja2 variables instead of relying on JS program.merchant_name which
was not in the ProgramResponse schema.

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

app/modules/loyalty/routes/pages/admin.py

@@ -15,9 +15,15 @@ from sqlalchemy.orm import Session
 from app.api.deps import get_db, require_menu_access
 from app.modules.core.utils.page_context import get_admin_context
 from app.modules.enums import FrontendType
-from app.modules.tenancy.models import User
+from app.modules.tenancy.models import Merchant, User
 from app.templates_config import templates
 
+
+def _get_merchant_name(db: Session, merchant_id: int) -> str:
+    """Look up merchant name for page header context."""
+    merchant = db.query(Merchant).filter(Merchant.id == merchant_id).first()
+    return merchant.name if merchant else ""
+
 router = APIRouter()
 
 # Route configuration for module route discovery
@@ -139,9 +145,10 @@ async def admin_loyalty_merchant_cards(
     Render merchant loyalty cards list page.
     Shows all loyalty cards for a specific merchant.
     """
+    merchant_name = _get_merchant_name(db, merchant_id)
     return templates.TemplateResponse(
         "loyalty/admin/merchant-cards.html",
-        get_admin_context(request, db, current_user, merchant_id=merchant_id),
+        get_admin_context(request, db, current_user, merchant_id=merchant_id, merchant_name=merchant_name),
     )
 
 
@@ -161,9 +168,10 @@ async def admin_loyalty_merchant_card_detail(
     Render merchant loyalty card detail page.
     Shows detailed info for a specific loyalty card.
     """
+    merchant_name = _get_merchant_name(db, merchant_id)
     return templates.TemplateResponse(
         "loyalty/admin/merchant-card-detail.html",
-        get_admin_context(request, db, current_user, merchant_id=merchant_id, card_id=card_id),
+        get_admin_context(request, db, current_user, merchant_id=merchant_id, card_id=card_id, merchant_name=merchant_name),
     )
 
 
@@ -182,9 +190,10 @@ async def admin_loyalty_merchant_transactions(
     Render merchant loyalty transactions list page.
     Shows all loyalty transactions for a specific merchant.
     """
+    merchant_name = _get_merchant_name(db, merchant_id)
     return templates.TemplateResponse(
         "loyalty/admin/merchant-transactions.html",
-        get_admin_context(request, db, current_user, merchant_id=merchant_id),
+        get_admin_context(request, db, current_user, merchant_id=merchant_id, merchant_name=merchant_name),
     )
 
 
@@ -203,9 +212,10 @@ async def admin_loyalty_merchant_pins(
     Render merchant staff PINs page (read-only).
     Shows all staff PINs for a specific merchant.
     """
+    merchant_name = _get_merchant_name(db, merchant_id)
     return templates.TemplateResponse(
         "loyalty/admin/merchant-pins.html",
-        get_admin_context(request, db, current_user, merchant_id=merchant_id),
+        get_admin_context(request, db, current_user, merchant_id=merchant_id, merchant_name=merchant_name),
     )