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/permadeath/Permadeath.kt

@@ -34,7 +34,8 @@ import java.util.concurrent.ConcurrentLinkedQueue
  *  - once a second, every online player's party and PC are swept for fainted Pokémon (one whose trainer was offline
  *    or in a battle when it fainted).
  * Settling: a Pokémon holding an item from `#cobblesurvival:revival_charms` is healed and the charm is used up;
- * any other is removed from its party or PC.
+ * any other is removed from its party or PC. The one exception is the player's starter (Adrian, 2026-11-09): it only
+ * faints, and can't be released or sacrificed either ([isStarter]; CobbleHardcoreMon's side is mixin/HardcorePartyMixin).
  */
 object Permadeath {
     val REVIVAL_CHARMS: TagKey<Item> =
@@ -50,6 +51,18 @@ object Permadeath {
         // CobbleHardcoreMon settles the battle at NORMAL priority; it has to see the revived Pokémon fainted.
         CobblemonEvents.BATTLE_ENDED.subscribe(Priority.HIGHEST, ::onBattleEnded)
         NeoForge.EVENT_BUS.addListener(::onServerTick)
+        CobblemonEvents.POKEMON_RELEASED_EVENT_PRE.subscribe(Priority.NORMAL) { event ->
+            if (!isStarter(event.pokemon)) return@subscribe
+            event.cancel()
+            event.player.sendSystemMessage(Component.translatableWithFallback("message.cobblesurvival.permadeath.starter_release",
+                "%s is your first partner: it can't be released.", event.pokemon.getDisplayName(false)).withStyle(ChatFormatting.YELLOW))
+        }
+    }
+
+    /** The Pokémon this player chose as a starter, which Cobblemon remembers for each player. */
+    fun isStarter(pokemon: Pokemon): Boolean {
+        val owner = pokemon.getOwnerUUID() ?: return false
+        return Cobblemon.playerDataManager.getGenericData(owner).starterUUID == pokemon.uuid
     }
 
     private fun onBattleFainted(event: BattleFaintedEvent) {
@@ -85,7 +98,7 @@ object Permadeath {
 
     private fun settle(player: ServerPlayer, pokemon: Pokemon) {
         val store = pokemon.storeCoordinates.get()?.store
-        if (!pokemon.isFainted() || (store !is PlayerPartyStore && store !is PCStore)) return
+        if (!pokemon.isFainted() || isStarter(pokemon) || (store !is PlayerPartyStore && store !is PCStore)) return
         // Faints during a battle are settled when it ends (above, and by CobbleHardcoreMon).
         if (player.isInBattle()) return
         try {