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/scripts/jx.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+"""Jar inspection without unzip/java.
+
+  jx.py ls    JAR[!nested.jar...] [regex]       list entries
+  jx.py cat   JAR[!nested.jar...] entry         print entry
+  jx.py str   JAR[!nested.jar...] classregex strregex   UTF8 constants of classes
+"""
+import io, re, struct, sys, zipfile
+
+
+def open_jar(spec):
+    parts = spec.split("!")
+    z = zipfile.ZipFile(parts[0])
+    for p in parts[1:]:
+        z = zipfile.ZipFile(io.BytesIO(z.read(p)))
+    return z
+
+
+def utf8_consts(data):
+    out = []
+    if data[:4] != b"\xca\xfe\xba\xbe":
+        return out
+    n = struct.unpack(">H", data[8:10])[0]
+    i, k = 10, 1
+    while k < n:
+        tag = data[i]
+        if tag == 1:
+            ln = struct.unpack(">H", data[i + 1:i + 3])[0]
+            out.append(data[i + 3:i + 3 + ln].decode("utf-8", "replace"))
+            i += 3 + ln
+        elif tag in (3, 4):
+            i += 5
+        elif tag in (5, 6):
+            i += 9; k += 1
+        elif tag in (7, 8, 16, 19, 20):
+            i += 3
+        elif tag in (9, 10, 11, 12, 17, 18):
+            i += 5
+        elif tag == 15:
+            i += 4
+        else:
+            break
+        k += 1
+    return out
+
+
+def main():
+    cmd, spec = sys.argv[1], sys.argv[2]
+    z = open_jar(spec)
+    if cmd == "ls":
+        rx = re.compile(sys.argv[3]) if len(sys.argv) > 3 else None
+        for n in z.namelist():
+            if not rx or rx.search(n):
+                print(n)
+    elif cmd == "cat":
+        sys.stdout.write(z.read(sys.argv[3]).decode("utf-8", "replace"))
+    elif cmd == "str":
+        crx, srx = re.compile(sys.argv[3]), re.compile(sys.argv[4])
+        for n in z.namelist():
+            if n.endswith(".class") and crx.search(n):
+                hits = [s for s in utf8_consts(z.read(n)) if srx.search(s)]
+                if hits:
+                    print("==", n)
+                    for h in hits:
+                        print("  ", repr(h))
+
+
+main()