refactor(templates): add error toast support to page templates

Update all page templates to accept an optional error message parameter
and display it via the ErrorToast component when data loading fails.

templates/dashboard.templ

@@ -5,7 +5,7 @@ import (
 	"fmt"
 )
 
-templ Dashboard(user User, sections []handlers.SectionData, libData []LibraryData, currentLibraryID string) {
+templ Dashboard(user User, sections []handlers.SectionData, libData []LibraryData, currentLibraryID string, errorMessage string) {
 	<!DOCTYPE html>
 	<html lang="en">
 	<head>
@@ -72,6 +72,8 @@ templ Dashboard(user User, sections []handlers.SectionData, libData []LibraryDat
 
 		<!-- Dashboard Settings Modal -->
 		@DashboardSettingsModal(sections)
+
+		@ErrorToast(errorMessage)
 	</body>
 	</html>
 }