feat(bench): automate B7 shader profiles, wire B12b trials, settle 45s

- gen_shader_profiles.py + shader-profiles/: Iris per-pack option files
  resolved from each pack's profile.* lines (Iris has no profile key)
- bench.py: flag rows shader_not_loaded when Iris falls back to vanilla
  rendering (analyze.py treats it as invalid)
- matrix: shader_options session key, trial jar globs pinned to the
  downloaded Modrinth builds, post-join settle 45 s (B0 v1 showed rep 1
  still warming at 10 s)

analysis/client-perf/harness/shader-profiles/ComplementaryReimagined_r5.9.3.LOW.txt

@@ -0,0 +1,18 @@
+# Iris options reproducing profile.LOW of ComplementaryReimagined_r5.9.3.zip
+# pack sha256 fed6c879e732cf7fc7bc6570ebb1def43235aa7e96f62859fbdbdbfa0b484b38
+# generated by gen_shader_profiles.py - do not edit; Iris rewrites the live
+# copy keeping only non-default values (bench.py journals and restores it)
+SHADOW_QUALITY=0
+shadowDistance=96.0
+WATER_REFLECT_QUALITY=2
+BLOCK_REFLECT_QUALITY=1
+LIGHTSHAFT_QUALI_DEFINE=0
+SSAO_QUALI_DEFINE=2
+FXAA_DEFINE=-1
+DETAIL_QUALITY=2
+CLOUD_QUALITY=2
+ANISOTROPIC_FILTER=0
+COLORED_LIGHTING=0
+WORLD_SPACE_REFLECTIONS=-1
+ENTITY_SHADOW=-1
+RAIN_PUDDLES=0