chore: make declarations private if they don't need to be public

This change is 99%  s/pub//   + a handful of dead code removal.

src/Notification.zig

@@ -253,7 +253,7 @@ pub const RequestDone = struct {
 };
 
 pub const RequestFail = struct {
-    pub const BlockedReason = enum {
+    const BlockedReason = enum {
         inspector,
     };