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>

pack/pack.toml

@@ -6,7 +6,7 @@ pack-format = "packwiz:1.1.0"
 [index]
 file = "index.toml"
 hash-format = "sha256"
-hash = "b2c6b7b6b2cb01942dc1c17c6526bc83ee1cbe7f4857e8af4557c2c9b4b4117a"
+hash = "72d088fe084f47754358b2ac5d723323f70779850de3e7135470bb1f45bcb3f4"
 
 [versions]
 minecraft = "1.21.1"