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/audit/extract.py

@@ -0,0 +1,48 @@
+import zipfile, io, json, tomllib, re, pickle, os, glob
+def lenient_json(b):
+    s=b.decode("utf-8-sig",errors="replace")
+    try: return json.loads(s)
+    except Exception:
+        s2=re.sub(r'//[^\n]*','',s); s2=re.sub(r',(\s*[}\]])',r'\1',s2)
+        try: return json.loads(s2)
+        except Exception: return None
+mods={}   # modid -> dict(jar, version, deps, nested)
+files=[]  # (jar, path, json) for data recipe/tags + lang
+lang={}; models=set(); errors=[]
+def walk(z, jarname, nested=False):
+    names=z.namelist()
+    for t in ("META-INF/neoforge.mods.toml","META-INF/mods.toml"):
+        if t in names:
+            raw=z.read(t).decode("utf-8",errors="replace")
+            try: m=tomllib.loads(raw)
+            except Exception as e: errors.append((jarname,"toml",str(e))); m={}
+            for md in m.get("mods",[]):
+                mid=md.get("modId"); ver=str(md.get("version"))
+                if ver.startswith("${"):
+                    mf=z.read("META-INF/MANIFEST.MF").decode(errors="replace") if "META-INF/MANIFEST.MF" in names else ""
+                    mm=re.search(r'Implementation-Version: *(\S+)',mf); ver=mm.group(1) if mm else ver
+                deps=m.get("dependencies",{}).get(mid,[])
+                mods.setdefault(mid,[]).append(dict(jar=jarname,version=ver,deps=deps,nested=nested,file=t))
+            break
+    for n in names:
+        if n.startswith("META-INF/jarjar/") and n.endswith(".jar"):
+            try: walk(zipfile.ZipFile(io.BytesIO(z.read(n))), jarname+"!"+n.split("/")[-1], True)
+            except Exception as e: errors.append((jarname,n,str(e)))
+        elif n.startswith("data/") and n.endswith(".json"):
+            p=n.split("/")
+            if len(p)>=4 and (p[2] in("recipe","recipes") or (p[2]=="tags" and p[3] in("item","items","block","blocks"))):
+                j=lenient_json(z.read(n))
+                if j is None: errors.append((jarname,n,"badjson"))
+                files.append((jarname,n,j))
+        elif n.startswith("assets/") and n.endswith("lang/en_us.json"):
+            j=lenient_json(z.read(n))
+            if isinstance(j,dict):
+                for k,v in j.items():
+                    if k.startswith(("item.","block.")) and k.count(".")==2: lang.setdefault(k,[]).append((jarname,v))
+        elif n.startswith("assets/") and "/models/item/" in n and n.endswith(".json"):
+            p=n.split("/"); models.add(p[1]+":"+"/".join(p[4:])[:-5])
+jars=["base_minecraft.jar","base_neoforge.jar"]+sorted(glob.glob("jars/*.jar"))
+for j in jars: walk(zipfile.ZipFile(j), os.path.basename(j))
+pickle.dump(dict(mods=mods,files=files,lang=lang,models=models,errors=errors),open("data.pkl","wb"))
+print(len(mods),len(files),len(lang),len(models),len(errors))
+for e in errors[:20]: print(e)