mountedRef was initialized to true but never reset on mount. The
cleanup function (useEffect return) set it to false on unmount. In
React 18 Strict Mode, components mount-unmount-remount during dev.
After the first cleanup, mountedRef stayed false forever.
Result: handlePunch set submitting=true, geolocation callbacks fired,
but every callback returned early at `if (!mountedRef.current) return`
before calling submitPunch. No server request, button stuck.
Fix: add `mountedRef.current = true` inside the useEffect body.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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