docs: client-perf analysis, bench harness and work journal

Everything the next agent needs to run the Phase 2 optimisation loop on a
machine that can launch the client:

- analysis/client-perf/: LEVERS (ranked levers + corrections), BENCH-MATRIX
  (world, scenes, config IDs, blocks B0-B14 with decision rules),
  PLAYER-TUNING, SPAWN-TUNING, research briefs, the jar scanner and its
  output, observed default configs, and proposed-configs/ (build.py
  generates tiers and bench variants and fails on unknown keys;
  apply_variant.py applies a variant and merges options.txt).
- analysis/client-perf/bench/onion-bench/: bench-world datapack (scene
  teleports, Create grid, mob pen, sound storm, 120 s teleport tour).
- analysis/audit/: the static recipe/dependency audit, including gen_fixes.py,
  which generates the shipped Paxi datapack and was never tracked.
- phase0/: per-machine measurement harness (Steam Deck, 7700K/1060,
  6700K/1080 Ti).
- .pi/journal.md: running work log; read it first.

All of it is packwizignored, so nothing here ships to players.

analysis/client-perf/data/observed-default-configs/alexscaves-client.toml

@@ -0,0 +1,35 @@
+[visuals]
+	#whether to cave maps are visible when held by players from the third-person perspective.
+	cave_maps_visible_in_third_person = true
+	#whether to shake the screen from tremorsaurus stomping, nuclear explosions, etc.
+	screen_shaking = true
+	#true if some block models, like uranium ore or abyssmarine bricks render as fullbright. May increase load time, no gameplay performance impact.
+	emissive_block_models = true
+	#whether to make the screen flash white during nuclear explosions.
+	nuclear_bomb_flash = true
+	#true if some biomes, such as primordial caves, have ambient light that makes the biome easier to see in.
+	biome_ambient_light = true
+	#true if some biomes, such as toxic caves, apply a color to ambient light. May conflict with shaders.
+	biome_ambient_light_coloring = true
+	#true if some biomes, such as primordial caves, have an always well-lit sky when in them. May conflict with shaders.
+	biome_sky_overrides = true
+	#true if some biomes, such as abyssal chasm, have an thicker water fog to them. May conflict with shaders.
+	biome_sky_fog_overrides = true
+	#true if ambersol block renders with rays of light emerging from it.
+	ambersol_shines = true
+	#true if irradiated effect makes mobs glow. May conflict with shaders.
+	radiation_glow_effect = true
+	#determines how far to the left the subterranodon flight indicator renders on the screen when mounted. Negative numbers will render it on the right. 
+	# Default: 22
+	# Range: -12000 ~ 12000
+	subterranodon_indicator_x = 22
+	#determines how far from bottom the subterranodon flight indicator renders on the screen when mounted.
+	# Default: 6
+	# Range: -12000 ~ 12000
+	subterranodon_indicator_y = 6
+	#true if sugar rush makes the world more saturated. May conflict with shaders.
+	sugar_rush_saturation_effect = true
+
+[audio]
+	#whether nuclear explosions briefly muffle other sounds.
+	nuclear_bomb_muffles_sounds = true