Phase 9: Iris and Complementary Reimagined, off by default

Adrian, 2026-11-09: set up the shader but keep it disabled by default. Iris
1.8.14-beta.1 (built for the pack's Sodium 0.8.13) and Complementary Reimagined
r5.9.3, both client only and fetched from Modrinth. Default Options' extra
folder ships config/iris.properties with shaders off and Complementary
preselected, copied only when a player has none. Toggle Shaders is on M, the
only free letter; Iris's other keys are unbound. tools/build.py fails if the
settings name a shader file the pack doesn't install.

Smoke test passes; client dependencies are satisfied. Not launched on a client.

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

docs/checklists/phase-9.md

@@ -9,6 +9,7 @@
 - **Ore veins:** rarer nodes and wider vein spacing, one block larger in radius. Needs a new island: the save "Cobblemon Survival Island (new veins)" has it. Your other saves keep their old veins.
 - **Respawn block:** much fainter glass; you aim through it unless sneaking. Automated: `regenerator_lets_the_aim_through`.
 - **Legend summons:** 22 Sigils, crafted from late-game materials (search "Sigil" in JEI). Used in the zone written on one, it summons a catchable legend that fights like a boss. Automated: `every_implemented_pokemon_is_obtainable`, `sigil_summons_a_catchable_legend`. The Legends chapter in the quest book lists them.
+- **Shaders:** Iris and Complementary Reimagined are installed, off by default.
 - **Left-out Pokémon:** 31 lines (67 species) spawn rarely in fitting zones (`docs/zone-species.md`). Automated: `spawn_pools_are_zoned`, `drop_sources_match_the_server`.
 
 ## In game (Prism instance)
@@ -16,6 +17,7 @@
 - [ ] In the new save, mine into an ore node or vein: the mined blocks turn into faint glass, and you can keep aiming and mining the ore behind them. Sneak and use one: its info still shows.
 - [ ] Do nodes and veins feel right: fewer, bigger? The island has 1.5–3× the old ore; tell me if that's too much.
 - [ ] Give yourself a Sigil from JEI (creative) and use it outside its zone: it refuses and says where it works. Use it in its zone: the legend appears with a sound and particles. Fight it: area attacks, at most a quarter of its HP per attack. Weaken it and catch it; afterwards it's an ordinary Pokémon in your party (no quarter-HP limit in later battles).
+- [ ] A fresh instance starts without shaders. Press M: Complementary Reimagined switches on (your existing instance has none of Iris's settings yet, so it starts off too; press M, or pick it in Video Settings > Shader Packs). Look at Pokémon, machine and boss particles, the glass cores and the respawn block with it on. How's the frame rate?
 - [ ] Is a Sigil the right cost, and the fight the right difficulty?
 - [ ] Spend time in Frostpeak or the Deep Sea: now and then a Beartic, Mamoswine, Empoleon or Walrein turns up. JEI's Island Drops page names the zone.