feat(perf): ship ModernFix dynamic_resources, add Flerovium and Iris Flywheel Compat

Bench (proxy 9900X/7800XT, see analysis/client-perf/RESULTS-proxy.md):
- ModernFix mixin.perf.dynamic_resources=true: startup -7.6 s, S1 p99
  9.11 -> 8.48 ms, S2 1% low 236 -> 264 fps (B6). Enforced packwiz file
  because ModernFix reads it before Default Options. Missing-texture check
  waived by owner; issues to be reported from play.
- Flerovium 1.1.2 (client): mob-pen S3 p99 ~0.9 ms better (B12b).
- Iris Flywheel Compat 2.4.0 (client): with a shaderpack, Create floor
  p99 13.3 -> 4.0 ms (Flywheel instancing kept under Iris) (B12b).
Deck tier already ships DH's LOW quality preset, so no DH change.

mods/flerovium.pw.toml

@@ -0,0 +1,13 @@
+name = "Flerovium"
+filename = "flerovium-neoforge-1.21.1-1.1.2-all.jar"
+side = "client"
+
+[download]
+url = "https://cdn.modrinth.com/data/4Rh1Mobu/versions/oU1q3eIj/flerovium-neoforge-1.21.1-1.1.2-all.jar"
+hash-format = "sha512"
+hash = "6301ea6991768832fa983f61e1b0574336aea4920e027632a3df93c8a10f5d87041876fad516d16827d9cd13a84b5a8c334c1a0076ca04121e321939d5d6ea52"
+
+[update]
+[update.modrinth]
+mod-id = "4Rh1Mobu"
+version = "oU1q3eIj"

mods/iris-flw-compat.pw.toml

@@ -0,0 +1,13 @@
+name = "Iris & Oculus Flywheel Compat"
+filename = "iris-flywheel-compat-NeoForge-2.4.0.jar"
+side = "client"
+
+[download]
+url = "https://cdn.modrinth.com/data/ndHYMY2K/versions/6ZQz5Ow2/iris-flywheel-compat-NeoForge-2.4.0.jar"
+hash-format = "sha512"
+hash = "192e5f00f2c146d2920867d7cd691ecec7ddd2acfb95880cc59084e8949225db92ecfb9221ba7223fc924ec43f2ca861115f83f9dc3f79e14a2f2a8db5287070"
+
+[update]
+[update.modrinth]
+mod-id = "ndHYMY2K"
+version = "6ZQz5Ow2"