internal: Make static analysis more happy (#8767)

* make functions used in 1 file static

* fix invalid substr param -1

* give default initializer to borderGradier

* move RASSERT from printf to std::print

src/helpers/Monitor.cpp

@@ -24,7 +24,7 @@
 using namespace Hyprutils::String;
 using namespace Hyprutils::Utils;
 
-int ratHandler(void* data) {
+static int ratHandler(void* data) {
     g_pHyprRenderer->renderMonitor(((CMonitor*)data)->self.lock());
 
     return 1;