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/entity_texture_features.json

@@ -0,0 +1,41 @@
+{
+  "optifine_limitRandomVariantGapsBy10": false,
+  "optifine_allowWeirdSkipsInTrueRandom": true,
+  "optifine_preventBaseTextureInOptifineDirectory": true,
+  "illegalPathSupportMode": "None",
+  "enableCustomTextures": true,
+  "enableCustomBlockEntities": true,
+  "textureUpdateFrequency_V2": "Fast",
+  "enableEmissiveTextures": true,
+  "enableEnchantedTextures": true,
+  "enableEmissiveBlockEntities": true,
+  "emissiveRenderMode": "DULL",
+  "alwaysCheckVanillaEmissiveSuffix": true,
+  "enableArmorAndTrims": true,
+  "skinFeaturesEnabled": true,
+  "skinTransparencyMode": "ETF_SKINS_ONLY",
+  "skinTransparencyInExtraPixels": true,
+  "skinFeaturesEnableTransparency": true,
+  "skinFeaturesEnableFullTransparency": false,
+  "tryETFTransparencyForAllSkins": false,
+  "enableEnemyTeamPlayersSkinFeatures": true,
+  "enableBlinking": true,
+  "blinkFrequency": 150,
+  "blinkLength": 1,
+  "advanced_IncreaseCacheSizeModifier": 1.0,
+  "debugLoggingMode": "None",
+  "logTextureDataInitialization": false,
+  "hideConfigButton": false,
+  "stackDebugPrinting": false,
+  "configButtonLoc": "BOTTOM_RIGHT",
+  "disableVanillaDirectoryVariantTextures": false,
+  "use3DSkinLayerPatch": true,
+  "enableFullBodyWardenTextures": true,
+  "entityEmissiveOverrides": {},
+  "propertiesDisabled": [],
+  "propertyInvertUpdatingOverrides": [],
+  "entityRandomOverrides": {},
+  "entityEmissiveBrightOverrides": {},
+  "entityRenderLayerOverrides": {},
+  "entityLightOverrides": {}
+}