Phase 9: reproducible builds, balance from the server, spark check, play feedback

Build: every tool pinned (JDK, packwiz, Gradle plugins, Python packages), exports
normalised, tools/check_reproducible.py proves two clean builds are byte-identical.

Server-side balance: a server can load config/cobblesurvival/datapack.zip in place of
the jar's data, /reload applies it, tools/server_update.py packages it and refuses
when a client change is needed. JEI drop pages are sent by the server. Code-held
balance numbers moved to tuning/server.json.

Performance: spark in the pack (server only), tools/perf_test.py with fake players
whose chunks really are active, docs/performance.md.

Adrian's feedback: default keys R, U, J, §; drop pages link to Cobblemon Info and show
real chances; bosses only hurt in battles; battle XP halved; channels between the
islands low level; temperature ×3 with insulation doubled; hazards start at once; no
item dots on the map; a wild attack starts a battle; the starter only faints; quest
book on join with a basics page and an HMs page; regional forms obtainable.

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

mod/src/main/kotlin/dev/cobblesurvival/zone/ZoneHazards.kt

@@ -29,6 +29,8 @@ import java.util.UUID
  * apples still work against it. Definitions: `data/cobblesurvival/zone_hazards/<name>.json`.
  */
 object ZoneHazards : SimpleJsonResourceReloadListener(Gson(), "zone_hazards") {
+    private const val CHECK_TICKS = 10
+
     class Hazard(
         val zone: String,
         val effect: Holder<MobEffect>,
@@ -72,7 +74,7 @@ object ZoneHazards : SimpleJsonResourceReloadListener(Gson(), "zone_hazards") {
 
     private fun onServerTick(event: ServerTickEvent.Post) {
         if (hazards.isEmpty()) return
-        val tick = event.server.tickCount
+        if (event.server.tickCount % CHECK_TICKS != 0) return
         for (player in event.server.playerList.players) {
             if (player.isCreative || player.isSpectator) continue
             val zone = Zones.at(player.serverLevel(), player.blockPosition())?.id
@@ -81,7 +83,10 @@ object ZoneHazards : SimpleJsonResourceReloadListener(Gson(), "zone_hazards") {
                 continue
             }
             for (hazard in hazards) {
-                if (hazard.zone != zone || tick % hazard.everyTicks != 0 || isProtected(player, hazard)) continue
+                if (hazard.zone != zone || isProtected(player, hazard)) continue
+                // At once on entering the zone (Adrian, 2026-11-09), then renewed every every_ticks.
+                val current = player.getEffect(hazard.effect)
+                if (current != null && current.duration > hazard.durationTicks - hazard.everyTicks) continue
                 player.addEffect(MobEffectInstance(hazard.effect, hazard.durationTicks, hazard.amplifier))
                 if (hazard.warning != null && warned[player.uuid] != zone) {
                     warned[player.uuid] = zone