perf(memory): optimize C++ string operations to reduce heap fragmentation

- Replaced pass-by-value std::string parameters with const std::string&
or std::string_view to prevent SSO overallocations.

- Refactored static mapping functions in UPower to return
std::string_view instead of constructing std::string literals, enabling
perfect cache locality.

- Optimized string concatenation in hot loops (network IPs, inhibitor
lists, sway window marks) by using std::string::append() and
pre-reserving capacity instead of overloaded operator+ which produces
temporary heap instances.

These optimizations reduce high-frequency memory churn and overall heap
fragmentation within the main rendering loops.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

src/modules/sway/bar.cpp

@@ -60,7 +60,7 @@ BarIpcClient::BarIpcClient(waybar::Bar& bar) : bar_{bar} {
   });
 }
 
-bool BarIpcClient::isModuleEnabled(std::string name) {
+bool BarIpcClient::isModuleEnabled(const std::string& name) {
   for (const auto& section : {"modules-left", "modules-center", "modules-right"}) {
     if (const auto& modules = bar_.config.get(section, {}); modules.isArray()) {
       for (const auto& module : modules) {