Refactor memory utilities: unify validation logic, adjust return types, and clean up main.zig formatting.

src/main.zig

@@ -28,7 +28,7 @@ pub fn main(init: std.process.Init) !void
 
     const allocator = if (debug) gpa.allocator() else std.heap.smp_allocator;
 
-    var tmp_arena: ?std.heap.ArenaAllocator  = .init(allocator);
+    var tmp_arena: ?std.heap.ArenaAllocator = .init(allocator);
     errdefer _ = zocket.memory.deinitIfExists(&tmp_arena);
 
     const tmp_allocator = tmp_arena.?.allocator();