remove concept of prod and dev assets

instead always do the "prod" thing, but use entr for restarting the
server for all assets

_do_run_server

@@ -1,6 +1,7 @@
 #!/bin/sh
 
 source ./_build_vars
+./_do_gen_assets
 go run \
     -tags "$(tr '\n' ' ' < _build_tags)" \
     cmd/gonic/main.go \