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/ferritecore-mixin.toml

@@ -0,0 +1,24 @@
+#Use a slightly more compact, but also slightly slower representation for block states
+compactFastMap = false
+#Replace objects used to detect multi-threaded access to chunks by a much smaller field. This option is disabled by default due to very rare and very hard-to-reproduce crashes, use at your own risk!
+useSmallThreadingDetector = false
+#Cache the predicate instances used in multipart models
+cacheMultipartPredicates = true
+#Do not create a new MultipartBakedModel instance for each block state using the same multipartmodel. Requires cacheMultipartPredicates to be enabled
+multipartDeduplication = true
+#Deduplicate cached data for blockstates, most importantly collision and render shapes
+blockstateCacheDeduplication = true
+#Save memory overhead from empty data component maps/patched
+dataComponentPatch = true
+#Avoid creation of new strings when creating ModelResourceLocations
+modelResourceLocations = true
+#Use smaller data structures for "simple" models, especially models with few side-specific faces
+modelSides = true
+#Replace the blockstate neighbor table
+replaceNeighborLookup = true
+#Populate the neighbor table used by vanilla. Enabling this slightly increases memory usage, but can help with issues in the rare case where mods access it directly.
+populateNeighborTable = false
+#Do not store the properties of a state explicitly and read themfrom the replace neighbor table instead. Requires replaceNeighborLookup to be enabled
+replacePropertyMap = true
+#Deduplicate vertex data of baked quads in the basic model implementations
+bakedQuadDeduplication = true