talk, chat: disables scry in hoon eval

We don't care about the static types in the use-cases where we need to
prevent scry (to prevent accidental data disclosure). We can evaluate
the expression, virtualized and untyped, and then just clam.

pkg/arvo/app/talk.hoon

@@ -1331,10 +1331,19 @@
         ::  executes {exe} and sends both its code and
         ::  result.
         ::
-        |=  {txt/cord exe/hoon}
-        =>  |.([(sell (slap (slop hoon-head seed) exe))]~)
-        =+  tan=p:(mule .)
-        (say [%exp txt tan] ~)
+        |=  [txt=cord exe=hoon]
+        ::  XX revisit
+        ::
+        ::    this double-virtualizes and clams to disable .^
+        ::
+        =;  tan=(list tank)
+          (say [%exp txt tan] ~)
+        ;;  (list tank)
+        =<  +>
+        %+  mong
+          :-  mute
+          |.([(sell (slap (slop hoon-head seed) exe))]~)
+        |=(^ ~)
       ::
       ++  target
         ::    %target

pkg/arvo/lib/hall-json.hoon

@@ -577,7 +577,17 @@
     :+  ~  u.exp
     =+  res=((ot res+(ar dank) ~) a)
     ?^  res  u.res
-    p:(mule |.([(sell (slap !>(..^zuse) (ream u.exp)))]~))  ::TODO  oldz
+    ::  XX revisit
+    ::
+    ::    this double-virtualizes and clams to disable .^
+    ::    the subject of the eval should include [our now eny]
+    ::
+    ;;  (list tank)
+    =<  +>
+    %+  mong
+      :-  mute
+      |.([(sell (slap !>(..^zuse) (ream u.exp)))]~)
+    |=(^ ~)
   ::
   ++  atta                                              :::  attache
     ^-  $-(json (unit attache))