Phase 3: Alpha guardians, one per zone, back 5 hours after a defeat

- Companion mod (zone/Guardians.kt): each zone's guardian stands at the
  zone's sample point, appears when a player is within 96 blocks, stays
  within 24 blocks, is uncatchable and half again as big. Beating it in a
  battle gives every player in the battle its drops; it returns after 5
  hours of game time (Adrian: fixed spots, 5 hours). State lives in the
  world save; /cobblesurvival guardians lists it.
- tools/zone_spawns.py writes data/cobblesurvival/guardians/<zone>.json:
  the strongest walking (or swimming) Pokemon of the zone at band top + 5,
  with the drops from world/zones.json. Boss drops follow Adrian's rule:
  Icy Rocks before Sunscorch, Heat Rocks before Frostpeak.
- Goat Fur and Hoglin Hide recipes make 8 per rock, so one guardian's 3
  rocks pay for one full insulating set.
- Self-test guardian_appears_and_returns; hazard tests cleaned up; the
  zone generator reads Cobblemon's own entries from the field guide's
  hidden_spawns.

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

mod/src/main/kotlin/dev/cobblesurvival/CobbleSurvival.kt

@@ -7,6 +7,7 @@ import dev.cobblesurvival.dev.BiomePreview
 import dev.cobblesurvival.permadeath.Permadeath
 import dev.cobblesurvival.selftest.SelfTest
 import dev.cobblesurvival.world.OnlyPokemon
+import dev.cobblesurvival.zone.Guardians
 import dev.cobblesurvival.zone.ZoneCondition
 import dev.cobblesurvival.zone.Zones
 import net.minecraft.commands.Commands
@@ -55,6 +56,7 @@ class CobbleSurvival {
         Permadeath.register()
         ZoneCondition.register()
         NeoForge.EVENT_BUS.addListener(Zones::onAddReloadListeners)
+        Guardians.register()
         SelfTest.register()
     }
 
@@ -93,6 +95,11 @@ class CobbleSurvival {
                 source.sendSuccess({ Component.literal(text) }, false)
                 1
             })
+            .then(Commands.literal("guardians").executes { context ->
+                val lines = Guardians.status(context.source.server.overworld())
+                context.source.sendSuccess({ Component.literal(lines.joinToString("\n").ifEmpty { "no guardians loaded" }) }, false)
+                1
+            })
         if (SelfTest.enabled) root.then(SelfTest.command())
         event.dispatcher.register(root)
     }