perf(memory): eliminate deep copies in range-based for loops and lambdas

This commit addresses memory churn caused by implicit deep copies during traversal and allocation of complex structures:

- Replaced pass-by-value 'Json::Value' in std::ranges and range-based for loops with 'const auto&' or 'const Json::Value&' in Hyprland modules, preventing large JSON tree duplications on every update.

- Fixed implicit string and pair copies in UPower and CPU Frequency loops by converting 'auto' to 'const auto&' where possible.

- Added 'std::vector::reserve' calls before 'push_back' loops in MPRIS, Niri, and CFFI modules to prevent exponential vector reallocation during initialization.

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

src/modules/niri/language.cpp

@@ -32,6 +32,7 @@ void Language::updateFromIPC() {
   auto ipcLock = gIPC->lockData();
 
   layouts_.clear();
+  layouts_.reserve(gIPC->keyboardLayoutNames().size());
   for (const auto& fullName : gIPC->keyboardLayoutNames()) layouts_.push_back(getLayout(fullName));
 
   current_idx_ = gIPC->keyboardLayoutCurrent();