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/route_test.ludic

@@ -7,6 +7,7 @@ program RouteTest {
   numbers float
 
   function water_everywhere_but_land(x: float, z: float) -> bool { return x < 100.0 }
+  bind FishingWorld { is_water: fn water_everywhere_but_land }
 
   # the route: a landed fish goes into the pack
   function route_fishing_pack(t: Tick) -> void {
@@ -16,9 +17,6 @@ program RouteTest {
 
   function game_start() -> void {
     core_clear()
-    let w = new FishingWorld
-    w.is_water = fn water_everywhere_but_land
-    fishing_bind(w)
     core_add(fishing_system())
     let r = system_new("route.fishing_pack", PH_RESOLVE)
     r.tick = fn route_fishing_pack

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

@@ -1,16 +1,14 @@
 # a toy mechanic: casting a line. It uses ludic.base and nothing else.
-module toy_fishing
+module toy_fishing uses ludic_base
 numbers float
 import "ludic.base"
 export property Caught { species: int = 0, weight: float = 0.0 }
-export property FishingWorld { is_water: fn(float, float) -> bool = null }  # its port
-var world: FishingWorld = null
+export port FishingWorld { is_water: fn(float, float) -> bool }           # its port
 var dice: Rng = null
 var casts: int = 0
 export var caught: Queue<Caught> = null                                   # its facts
-export function fishing_bind(w: FishingWorld) -> void { world = w }
 export function fishing_cast(x: float, z: float) -> bool {                 # its verb
-  if not world.is_water(x, z) { return false }
+  if not FishingWorld.is_water(x, z) { return false }
   casts += 1
   return true
 }

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