ames/zuse: handle %trim event

pkg/arvo/sys/vane/ames.hoon

@@ -1094,6 +1094,7 @@
       %jilt  (on-jilt:event-core ship.task)
       %sift  (on-sift:event-core ships.task)
       %spew  (on-spew:event-core veb.task)
+      %trim  on-trim:event-core
       %vega  on-vega:event-core
       %plea  (on-plea:event-core [ship plea]:task)
     ==
@@ -1856,8 +1857,10 @@
     ::
     (emit unix-duct.ames-state %give %turf turfs)
   ::  +on-vega: handle kernel reload
+  ::  +on-trim: handle request to free memory
   ::
   ++  on-vega  event-core
+  ++  on-trim  event-core
   ::  +enqueue-alien-todo: helper to enqueue a pending request
   ::
   ::    Also requests key and life from Jael on first request.

pkg/arvo/sys/zuse.hoon

@@ -394,6 +394,7 @@
     ::    %init: vane boot
     ::    %sift: limit verbosity to .ships
     ::    %spew: set verbosity toggles
+    ::    %trim: release memory
     ::    %vega: kernel reload notification
     ::
     +$  task
@@ -408,6 +409,7 @@
           $>(%init vane-task)
           [%sift ships=(list ship)]
           [%spew veb=(list verb)]
+          $>(%trim vane-task)
           $>(%vega vane-task)
       ==
     ::  $gift: effect from ames