refactor(packages): the mechanic packages use ludic_base only, and ask through ports

ludic.clock, .effects, .inventory, .wallet, .weather and .tracks say
'uses ludic_base' (ludic.base uses nothing). ClockWorld, PackRules,
WeatherWorld and TracksWorld are export ports whose defaults are the old
fallbacks; clock_bind, inv_bind, weather_bind and tracks_bind are gone,
and the tests bind their fakes. The base README's toy does the same.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.base/tests/toys/pack/index.ludic

@@ -1,5 +1,5 @@
 # a toy mechanic: a pack of counts by kind, saved in its own section
-module toy_pack
+module toy_pack uses ludic_base
 numbers float
 import "ludic.base"
 var counts: []int = null