feat: modernize config

- config now is more toml like
- no need to declare all fields, it implements defaults
- no yanderedev code, introspection babbyyy 😎
- desktop and config files parser semi-unification
- misc tweaks all over (mainly allocation failures handling)

include/ui.h

@@ -4,7 +4,7 @@
 #include "config.h"
 #include "util.h"
 
-void setup(struct config);
+void setup(struct config* config);
 int load(struct Vector* users, struct Vector* sessions);
 void print_err(const char*);
 void print_errno(const char*);