[works] cleanups, wfc service architecture

- now using zj as a dep instead of just having it locally
- put WFC into its own service tree

  this surgery is not complete, but it has been started and the repo is
  currently not in a botched state

- deleted orphan "wsp" (web socket process) module

src/fd_httpd_client.erl

@@ -348,7 +348,7 @@ wfcin(Sock, #request{enctype = json,
                 {fd_httpd_utils:jsbad(ErrorMessage), Ctx0}
         end,
     % update cache with new context
-    ok = fd_cache:set(Cookie, NewCtx),
+    ok = fd_wfcd_cache:set(Cookie, NewCtx),
     Body    = zj:encode(RespObj),
     Response = #response{headers = [{"content-type", "application/json"},
                                     {"set-cookie",   ["wfc=", Cookie]}],
@@ -366,17 +366,9 @@ wfcin(Sock, Request) ->
          Context :: wfc_eval_context:context().
 
 ctx(#{<<"wfc">> := Cookie}) ->
-    case fd_cache:query(Cookie) of
+    case fd_wfcd_cache:query(Cookie) of
         {ok, Context} -> {Cookie, Context};
         error         -> {Cookie, wfc_eval_context:default()}
     end;
 ctx(_) ->
     {fd_httpd_utils:new_cookie(), wfc_eval_context:default()}.
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