Fix catalog redirects pointing at the old /ruoat

Adding, editing or deleting a dish redirected to /ruoat, which stopped
existing when the tab was renamed to Ruuat. Every one of those actions ended
on a 404. Shipped in v20260905-4.

The rename was done with a scripted replace across views.templ, main.go and
the smoke script; handlers.go was not in the list.

The tests did not catch it because they asserted only that the response was a
303. A redirect to a dead URL is still a 303. They now assert the target.

cmd/foodster/handlers.go

@@ -508,7 +508,7 @@ func (a *app) saveMain(w http.ResponseWriter, r *http.Request) {
 			log.Printf("save main: %v", err)
 			form.Err = "Tallennus epäonnistui."
 		default:
-			http.Redirect(w, r, "/ruoat", http.StatusSeeOther)
+			http.Redirect(w, r, "/ruuat", http.StatusSeeOther)
 			return
 		}
 	}
@@ -537,7 +537,7 @@ func (a *app) saveSide(w http.ResponseWriter, r *http.Request) {
 			log.Printf("save side: %v", err)
 			form.Err = "Tallennus epäonnistui."
 		default:
-			http.Redirect(w, r, "/ruoat", http.StatusSeeOther)
+			http.Redirect(w, r, "/ruuat", http.StatusSeeOther)
 			return
 		}
 	}
@@ -565,7 +565,7 @@ func (a *app) deleteDish(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "poisto epäonnistui", http.StatusInternalServerError)
 		return
 	}
-	http.Redirect(w, r, "/ruoat", http.StatusSeeOther)
+	http.Redirect(w, r, "/ruuat", http.StatusSeeOther)
 }
 
 // importDishes takes a bundle either pasted into the textarea or uploaded as a