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/tests/test_bench_flags.py

@@ -271,3 +271,13 @@ class OptionsAndFlags(unittest.TestCase):
 
 if __name__ == "__main__":
     unittest.main()
+
+
+class ShaderLoaded(unittest.TestCase):
+    def test_flags(self):
+        ok = ["[Render thread/INFO] [Iris/]: Using shaderpack: MakeUp-UltraFast-9.5f.zip"]
+        bad = ok + ["[Render thread/ERROR] [Iris/]: Failed to compile shaders"]
+        self.assertEqual(bench.shader_flags("off", []), [])
+        self.assertEqual(bench.shader_flags("X.zip", ok), [])
+        self.assertEqual(bench.shader_flags("X.zip", []), ["shader_not_loaded"])
+        self.assertEqual(bench.shader_flags("X.zip", bad), ["shader_not_loaded"])