Cleanup: Finalize template context integration and remove legacy code

- Replaced legacy TemplateContext calls with structured TemplateData usage
- Removed unused variables and redundant storage calls in notifications handler
- Ensured consistent use of BuildTemplateData across user-facing handlers
- Resolved all compile-time errors from refactor
- Ready for runtime testing and further layout integration

handlers/admin/prizes.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"strconv"
 	"synlotto-website/helpers"
+	"synlotto-website/models"
 )
 
 func AddPrizesHandler(db *sql.DB) http.HandlerFunc {
@@ -16,7 +17,7 @@ func AddPrizesHandler(db *sql.DB) http.HandlerFunc {
 				"templates/layout.html",
 				"templates/admin/draws/prizes/add_prizes.html",
 			))
-			tmpl.ExecuteTemplate(w, "layout", helpers.TemplateContext(w, r))
+			tmpl.ExecuteTemplate(w, "layout", helpers.TemplateContext(w, r, models.TemplateData{}))
 			return
 		}
 
@@ -50,7 +51,7 @@ func ModifyPrizesHandler(db *sql.DB) http.HandlerFunc {
 				"templates/layout.html",
 				"templates/admin/draws/prizes/modify_prizes.html",
 			))
-			tmpl.ExecuteTemplate(w, "layout", helpers.TemplateContext(w, r))
+			tmpl.ExecuteTemplate(w, "layout", helpers.TemplateContext(w, r, models.TemplateData{}))
 			return
 		}