chore: run live-sync heartbeat hourly

Operator decision at review: 15 min is aggressive for config churn; hourly
keeps the stale-window acceptable (<=1 h) with a fifth of the wakeups.
Timer unit, tier law, and failure-table wording aligned.

dotfiles/systemd-user/.config/systemd/user/live-sync.timer

@@ -1,9 +1,9 @@
 [Unit]
-Description=command-center live-sync heartbeat every 15 minutes
+Description=command-center live-sync heartbeat every hour
 
 [Timer]
 OnBootSec=5min
-OnUnitActiveSec=15min
+OnUnitActiveSec=1h
 RandomizedDelaySec=3min
 Persistent=true