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/immediatelyfast.json

@@ -0,0 +1,22 @@
+{
+  "REGULAR_INFO": "----- Regular config values below -----",
+  "font_atlas_resizing": true,
+  "map_atlas_generation": true,
+  "hud_batching": true,
+  "fast_text_lookup": true,
+  "fast_buffer_upload": true,
+  "COSMETIC_INFO": "----- Cosmetic only config values below (Does not optimize anything) -----",
+  "dont_add_info_into_debug_hud": false,
+  "EXPERIMENTAL_INFO": "----- Experimental config values below (Rendering glitches may occur) -----",
+  "experimental_disable_error_checking": false,
+  "experimental_disable_resource_pack_conflict_handling": false,
+  "experimental_sign_text_buffering": false,
+  "experimental_screen_batching": false,
+  "DEBUG_INFO": "----- Debug only config values below (Do not touch) -----",
+  "debug_only_and_not_recommended_disable_universal_batching": false,
+  "debug_only_and_not_recommended_disable_mod_conflict_handling": false,
+  "debug_only_and_not_recommended_disable_hardware_conflict_handling": false,
+  "debug_only_print_additional_error_information": false,
+  "debug_only_use_last_usage_for_batch_ordering": false,
+  "debug_only_detailed_memory_leak_detection": false
+}