Release 1.5

versionCode 6. public_html/ changed, so the service worker cache goes to
bgclock-v21.

Not confirmed on device: the force-quit-and-reopen check from RELEASING.md
step 4 has not been run for this build. Nothing in it touches storage, timing
or the state machine — the change is a label, an inherited colour and a lit
button, all written from render() — but the check is still owed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

public_html/sw.js

@@ -1,5 +1,5 @@
 /* Cache-first: once installed the clock never touches the network again. */
-const CACHE = "bgclock-v20";
+const CACHE = "bgclock-v21";
 const FILES = [
   "./",
   "./index.html",