Lower the battery threshold to 30% and default the cachy-update prompt to yes

The prompt offering to silence cachy-update's own update notification now
defaults to yes: once updates install themselves that notification is nothing
but noise, so the common answer should be the one you get by pressing Enter.

It also accepts "j" now. The prompt is translated, so a German user reads
"[J/n]" and types the German letter - which the old check for "y" alone
silently read as a refusal.

src/lib/config.sh

@@ -134,7 +134,7 @@ cau_config_load() {
 
 	CFG_INTERVAL="$(cau_config_get UpdateInterval 1d)"
 	CFG_INTERVAL_SECONDS="$(cau_duration_to_seconds "$CFG_INTERVAL" 86400)"
-	CFG_MIN_BATTERY="$(cau_config_int MinBatteryPercent 40)"
+	CFG_MIN_BATTERY="$(cau_config_int MinBatteryPercent 30)"
 	CFG_KEEP_OLD="$(cau_config_int KeepOldPackages 3)"
 	CFG_AUR_HELPER="$(cau_config_get AURHelper auto)"
 	CFG_IGNORE_PKG="$(cau_config_get IgnorePkg '')"