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>

docs/addon-status.md

@@ -62,6 +62,7 @@ JEI declares Minecraft `[1.21, 1.21.1)` in every 1.21.1 build, which a strict re
 | Cobblemon Info for REI / JEI / EMI | 8 | 2.32.14+neoforge (MR `bxd0xXZI`) | MR | ✅ Declares Cobblemon `[1.7.1,)`. **In the pack** (2026-11-03, Adrian), on both sides: it reads the server's live spawn pool (the pack's zone pools); a client on a server without it falls back to Cobblemon's own spawn files. Shows spawns, drops, evolutions; doesn't know the pack's zone rule, so it lists a spawn's biomes, not its zone. Self-test `jei_addon_shows_island_spawns` |
 | Quests & Teams Fixes (flexible-mode soft-lock fix) | 8 | — | MR | ❌ Only 1.20.1 builds exist. Test the soft-lock on FTB Quests 2101.1.37 ourselves |
 | Iris Shaders | 9 | 1.8.14-beta.1+1.21.1-neoforge (MR `KduFYu4t`) | MR + CF | n/a (no Cobblemon dependency). **In the pack** (2026-11-09), client only. A beta, and the only NeoForge 1.21.1 build for Sodium 0.8; built against the pack's Sodium 0.8.13 |
+| spark | 9 | 1.10.124 (MR `v5qtqRQi`, CF file `6225208`) | MR + CF | n/a (no Cobblemon dependency). **In the pack** (2026-11-09), server only: `tools/perf_test.py` and profiling during playtests |
 | Complementary Reimagined (shader pack) | 9 | r5.9.3 (MR `Bqen1mJX`) | MR + CF | n/a. **In the pack** (2026-11-09), off by default; client only |
 | spark | 9 | 1.10.124 (MR `v5qtqRQi`, CF `6225208`) | MR + CF | n/a |