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>

include/modules/sway/bar.hpp

@@ -37,7 +37,7 @@ class BarIpcClient {
   void onModeUpdate(bool visible_by_modifier);
   void onUrgencyUpdate(bool visible_by_urgency);
   void update();
-  bool isModuleEnabled(std::string name);
+  bool isModuleEnabled(const std::string& name);
 
   Bar& bar_;
   util::JsonParser parser_;