the correction gesture is step-up gated after all (V-630)

Trace ids are sequential integers and the label table is the one thing the
routing heads will be fitted on, so an ungated POST let anyone past the
transport gate mislabel turns the owner never touched.

The cost argument for leaving it open does not hold: he tapped to send the
turn he is correcting, so the session is already up when the buttons appear.

cmd/mavweb/main.go

@@ -210,13 +210,7 @@ func main() {
 	mux.HandleFunc("/routines", gatedPage(handleRoutines))
 	mux.HandleFunc("/api/chat", gatedPage(handleChatAPI))
 	mux.HandleFunc("/api/revert", gatedPage(handleRevert))
-	// POST /api/correct is deliberately NOT on the step-up list (V-630). It
-	// reaches no router, no model and no act path: it writes one label row that
-	// nothing executes from. A correction that costs a passkey tap is a
-	// correction the owner does not make, and then the table stays empty.
-	mux.HandleFunc("/api/correct", func(w http.ResponseWriter, r *http.Request) {
-		handleCorrectAPI(w, r, core)
-	})
+	mux.HandleFunc("/api/correct", gatedPage(handleCorrectAPI))
 	mux.HandleFunc("/models", func(w http.ResponseWriter, r *http.Request) {
 		handleModels(w, r, core, swapConn, stepUpSession, *requireStepUp)
 	})