bench: JSPI vs asyncify A/B — harness + results

Adds pcbnew-large-perf.spec.ts (PERF_LARGE-gated: repeated cold loads,
vme-wren/jetson opens, rAF + distinct-glcanvas-frame FPS under throttle,
wasm/JS heap checkpoints), fetchIntoMemfs + openAndWait/sampleMemory/
measureFpsDetailed perf-utils, dual 9.99+10.0 config seeding in pcbnew.html
so foreign-branch builds boot wizard-free, and the full benchmark report +
raw data under docs/features/async/migration-evidence/.

Headlines: wasm 94 vs 113 MB raw (18.6 vs 36.7 MB gzip), post-link tail
1.6 s/49 MB vs 63 s/6.1 GB per build, cold load −40 %, 27.7 MB board open
−45 %, real redraws +68 % at 4× throttle, boot heap −31 %.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016X9eh1s5sTx1o9Em9KBuwR

docs/features/async/migration-evidence/bench-data-2026-08/bundle-sizes.json

@@ -0,0 +1,66 @@
+{
+  "jspi": {
+    "kicad_editor.wasm": {
+      "raw": 98664038,
+      "gzip": 19469712,
+      "brotli": 14173019
+    },
+    "kicad_editor.js": {
+      "raw": 474692,
+      "gzip": 116955,
+      "brotli": 106125
+    },
+    "wx.js": {
+      "raw": 74281,
+      "gzip": 17356,
+      "brotli": 16439
+    },
+    "wx-dom.js": {
+      "raw": 63269,
+      "gzip": 16857,
+      "brotli": 15848
+    },
+    "images.tar.gz": {
+      "raw": 5370904,
+      "gzip": 5372562,
+      "brotli": 5114985
+    },
+    "TOTAL": {
+      "raw": 104647184,
+      "gzip": 24993442,
+      "brotli": 19426416
+    }
+  },
+  "asyncify": {
+    "kicad_editor.wasm": {
+      "raw": 118557371,
+      "gzip": 38473650,
+      "brotli": 25666194
+    },
+    "kicad_editor.js": {
+      "raw": 472325,
+      "gzip": 116872,
+      "brotli": 105662
+    },
+    "wx.js": {
+      "raw": 74281,
+      "gzip": 17356,
+      "brotli": 16439
+    },
+    "wx-dom.js": {
+      "raw": 63041,
+      "gzip": 16773,
+      "brotli": 15765
+    },
+    "images.tar.gz": {
+      "raw": 5370145,
+      "gzip": 5371803,
+      "brotli": 5160999
+    },
+    "TOTAL": {
+      "raw": 124537163,
+      "gzip": 43996454,
+      "brotli": 30965059
+    }
+  }
+}