Refactor: Recover middleware now uses RenderError + add full notifications view

- Replaced http.Error with helpers.RenderError in Recover middleware
- Custom 500.html now rendered with layout and topbar on panic
- RenderError gracefully checks template existence and falls back to plain response
- Added /account/notifications full view page (index)
- Linked "Back to notifications" from notification read view
- Fixed typo in template path for notifications/index.html
- Improved layout consistency across error and account pages

handlers/notifications.go

@@ -15,7 +15,7 @@ func NotificationsHandler(db *sql.DB) http.HandlerFunc {
 		data := BuildTemplateData(db, w, r)
 		context := helpers.TemplateContext(w, r, data)
 
-		tmpl := helpers.LoadTemplateFiles("notifications.html", "templates/account/notifications.html")
+		tmpl := helpers.LoadTemplateFiles("index.html", "templates/account/notifications/index.html")
 
 		err := tmpl.ExecuteTemplate(w, "layout", context)
 		if err != nil {