Phase 8: the pack's own JEI pages for every drop source

Adrian, 2026-11-02/03: every item that can drop gets a JEI page naming its
sources, alongside the Cobblemon Info add-on (which shows drops and biomes,
not zones). The companion mod's JEI plugin (jei/DropSourcesJei.kt) adds:
- Pokemon drops on the island: 794 species of lines that live on the
  island, with chances, amounts and the zones they spawn in (or where their
  line lives); spawns with their own drops (Beheeyem in the End). The Drop
  Synthesizer core is the catalyst.
- Guardians and the End boss; Sacrifice Altar tiers and specials; Rebirth
  Chamber; zone ore veins with regrow times; Cobblebase pasture finds per
  skill and zone.

JEI runs on the client, so the pages read assets/cobblesurvival/jei/
drop_sources.json inside the mod, written by tools/jei_sources.py from the
pack's files. Self-tests drop_sources_match_the_server (file vs live server:
drops, zones, own-drop spawns, guardians, End boss, altar) and
jei_pages_build (every page builds, every item exists). The ore a vein gives
moved into world/zones.json (ores -> item), shared with the quest book.
JEI's API (19.64.0.455) is a compile-only dependency from JEI's own Maven.
Self-tests and the island check pass.

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

README.md

@@ -118,6 +118,13 @@ python3 tools/quests.py
 ```
 Generates the quest book (Phase 8) from `docs/quests.yaml` into `pack/config/ftbquests/quests/`, and the hidden advancements quests check. `tools/build.py` runs it. `--pull <FTB Quests folder>` first copies node positions moved in the in-game editor back into `docs/quests.yaml` (`tools/prism_instance.py` does it from the instance before each sync); `--check` fails if the generated files are out of date.
 
+## JEI drop sources
+
+```bash
+python3 tools/jei_sources.py
+```
+Writes the data behind the pack's own JEI pages (Phase 8) into the companion mod (`mod/src/main/resources/assets/cobblesurvival/jei/drop_sources.json`): every Pokémon's drops and zones, guardians, the End boss, the altar, ore veins, pasture finds. Run it after changing species drops, spawns, guardians, machines, ores or Cobblebase tables, then rebuild; the self-test `drop_sources_match_the_server` fails while it's stale. Needs the Cobblemon jar in `build/server/mods` (any test-server run).
+
 ## Adding a mod
 
 1. Read its license and its Cobblemon 1.8 status; add both to `docs/licenses.md` and `docs/addon-status.md`.