Refactor: merge duplicated rules, split the largest files by topic (t21)

- One helper each for wall and mold refunds, tube edges and lanes, pipe text, piece dimensions,
  font lookup, reach circles and surface averaging.
- previews, smooth, notebook, materials, worldgen and selection split into topic files
  (preview-drill, preview-selection, smooth-shaders, notebook-market, notebook-blueprints,
  material-tables, worldgen-helpers, selection-pickers, selection-panels).
- Every suite's output identical apart from timings; seeds make the same worlds.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/manifest.json

@@ -6,6 +6,7 @@
   "sim": [
     "sim/base.js",
     "sim/materials.js",
+    "sim/material-tables.js",
     "sim/pieces.js",
     "sim/economy.js",
     "sim/progress.js",
@@ -33,6 +34,7 @@
     "sim/ledger.js",
     "sim/weather.js",
     "sim/tick.js",
+    "sim/worldgen-helpers.js",
     "sim/worldgen.js",
     "sim/save.js"
   ],
@@ -43,6 +45,7 @@
     "render/machines.js",
     "render/overlays.js",
     "render/smooth.js",
+    "render/smooth-shaders.js",
     "ui/audio.js",
     "ui/state.js",
     "ui/title.js",
@@ -51,14 +54,20 @@
     "ui/session.js",
     "ui/settings.js",
     "ui/notebook.js",
+    "ui/notebook-market.js",
+    "ui/notebook-blueprints.js",
     "ui/hud.js",
     "ui/build-menu.js",
     "ui/selection.js",
+    "ui/selection-pickers.js",
+    "ui/selection-panels.js",
     "ui/info.js",
     "ui/input.js",
     "ui/actions.js",
     "ui/gamepad.js",
     "ui/previews.js",
+    "ui/preview-drill.js",
+    "ui/preview-selection.js",
     "ui/events.js",
     "ui/map.js",
     "ui/loop.js"