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/sable-client.toml

@@ -0,0 +1,21 @@
+#Whether sub-levels should apply block shading dynamically
+sub_level_dynamic_shading = true
+#Whether sub-levels can occlude the water surface
+sub_level_water_occlusion = true
+#Whether sub-levels should cast a shadow on the world
+sub_level_skylight_shadows = false
+#Whether to draw loaded chunks on the client in the chunk debug renderer
+debug_draw_loaded_chunks = false
+#The distance back in game-ticks that the snapshot interpolation should operate
+# Default: 1.5
+# Range: 0.0 ~ 100.0
+sub_level_snapshot_interpolation_delay_ticks = 1.5
+#The renderer to use for sub-levels
+#Allowed Values: SODIUM_REACHAROUND
+sub_level_renderer = "SODIUM_REACHAROUND"
+#The zoom sensitivity for sub-level camera types
+# Default: 0.2
+# Range: 0.0 ~ 100.0
+sub_level_zoom_sensitivity = 0.2
+#If Sable should attempt to establish a UDP connection with the server, to receive sub-level movement data over a UDP channel
+attempt_udp_networking = true