fix(battery): gate Full-as-Plugged behind full-at-plugged option, drop debug output

Reporting a full battery on AC as 'Plugged' is now opt-in via the
'full-at-plugged' config option (default false), so existing format-full /
tooltip-format-full setups keep working. Also documents the option.

man/waybar-battery.5.scd

@@ -27,6 +27,11 @@ The *battery* module displays the current capacity and state (eg. charging) of y
 	default: false ++
 	Option to use the battery design capacity instead of its current maximal capacity.
 
+*full-at-plugged*: ++
+	typeof: bool ++
+	default: false ++
+	When enabled, a battery that is *Full* while the adapter is online is reported with the *Plugged* status instead of *Full* (so you can style/format it separately). Disabled by default to preserve the existing *Full* behaviour.
+
 *interval*: ++
 	typeof: integer ++
 	default: 60 ++

src/modules/battery.cpp

@@ -706,7 +706,7 @@ auto waybar::modules::Battery::update() -> void {
   if (!adapter_.empty()) {
     std::ifstream(adapter_ / "online") >> adapter_online;
   }
-  if (status == "Full" && adapter_online) {
+  if (config_["full-at-plugged"].asBool() && status == "Full" && adapter_online) {
     status = "Plugged";
   }
   auto status_pretty = status;