fix(clipboard): copy toasts reflect the configured clear delay

The "clears in 30s" suffix was hardcoded in ~14 toasts. Single helper
clipClearSuffix() reads clipboardClearSeconds (''=Never); prefixes concatenated
to it. Cheatsheet text made generic "(auto-clears)".

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

js/app.unlock.js

@@ -733,10 +733,10 @@ async function doGenerateRecoveryKey() {
                 // running embedded, navigator.clipboard with manual scrub
                 // otherwise.
                 if (Bridge.copySecure(code, 30000)) {
-                    toast('Recovery code copied · clears in 30s');
+                    toast('Recovery code copied' + clipClearSuffix());
                 } else {
                     navigator.clipboard.writeText(code).then(() => {
-                        toast('Recovery code copied · clears in 30s');
+                        toast('Recovery code copied' + clipClearSuffix());
                         setTimeout(() => navigator.clipboard.writeText('').catch(()=>{}), 30000);
                     });
                 }