feedback5: merge feedback4 (3af5b84) — PRs #186 / #134 / #185 / #24 / #183 ported to the split layout (terrainInfo / TERRAIN_TIPS into a new ui/gameLogic/terrain.js re-exported by the gameLogic.js barrel, closesOnFieldPress into ui/gameLogic/shortcuts.js, the rest in place; 42 strings through t(), #183's 设置 too); golden unchanged

Ported by hand:
- public/js/ui/gameLogic.js is a re-export shim on feedback5: #185's TERRAIN_TIPS / terrainInfo went into the new
  public/js/ui/gameLogic/terrain.js (the barrel gains one re-export line); closesOnFieldPress 'terrain' into
  ui/gameLogic/shortcuts.js.
- i18n (docs/I18N.md): every new user-visible string goes through t() with an English entry in public/i18n/en.json
  (42, after the 补位 strings): the terrain names / tags / fact table are N_() and translated where terrainInfo hands
  them out, the mechanism lines are msgids with their numbers as params (a line with an optional half is two whole
  msgids, the list joins use an array param), the card's 地形机制 / 这一格 titles in ui/detailPanel.js. Official EN
  terms where the EN client has them (stage_table tileInfo: Active Originium, Mire, Exhaust Grille, Deep Water Zone,
  Incursion Point, Protection Objective, Tunnel Entry / Exit, High Ground; Camouflage). The Chinese output is
  byte-identical to feedback4's terrainInfo on all 5187 tiles of the 13 stages and on synthetic stages.
- public/js/screens/game.js (MatchScreen still lives there): the import keeps feedback5's names plus terrainInfo /
  fieldTile; the terrain stage is the one view.setStage gets, so it includes feedback5's fieldStage — a 联防 field is
  played on its own map (GitHub #41), and a tap there explains that map's tile, not the round stage's. The tileClick
  handler and render/app.js emitTileClick / ui/fallbackField.js auto-merged in place. terrainInfo reads the stage only,
  so a 补位 / 自选 board explains its tiles the same way (their pieces only change a piece's art and name).
- public/js/ui/detailPanel.js: the terrain branch of resolveDetail before feedback5's stand-in / 自选 helpers.
- public/js/screens/title.js (#183): feedback5's LangToggle / t() imports plus GIcon / SettingsModal; the gear
  button's aria-label / title are t('设置') (en.json already has "Settings").
- tools/fetch-assets.mjs / tools/assets/downloader.mjs: --add-only (keepExisting, the font skip) beside #24's
  --asset-source / SP_ASSET_SOURCE and the shared MirrorPolicy; feedback5's extraOperators / moduleTypes and the
  voice plan unchanged.
- data/assets.json: feedback5's manifest plus #134's audio.sfx.battle.leak (after heal, the plan order); stats files
  6993 → 6994 and bytes +23 240 as measured on feedback4; the hash recomputed with the generator's contentHash
  (c01aa739a2d3 → 6a547fc5c937). A field-wise JSON diff against feedback5 shows only those four fields.
- docs: DESIGN §24 intro and §24.5 / §24.6 as on feedback4 (the rest of DESIGN.md is feedback5's); ASSETS.md,
  DEPLOY.md, PLAYING.md auto-merged.
- Auto-merged and checked: audio.js (the sim still emits ['leak', id], server/sim/battle/deploy.js), render/style.js,
  textures.js, tiles.js, board3d/materials.js, boardArt.js, tools/assets/*, tools/setup.mjs, extract.py, the tests.

Checks: the PRs' unit tests (audio 22, gameLogic 44, terrain-detail 1, originium-art 4, boardart 15,
board3d-extract 9, asset-network 21, fetch-assets-shrink 4), i18n 9 / i18n-data 8 / i18n-server 4, client-static 313,
docs-consistency 24, kits_layout 6 pass; lint 0 errors (no new warnings), check:imports, typecheck; golden: all 283
scenarios match, nothing regenerated.

public/js/render/style.js

@@ -70,6 +70,37 @@ export const COLORS = Object.freeze({
 export const TIER_COLORS = Object.freeze([0x9aa5a0, 0x9aa5a0, 0x7fd37a, 0x52b6ff, 0xb98cff, 0xffc600, 0xff6b3d]);
 export const ENEMY_FRAME = Object.freeze({ normal: 0xc84a3c, elite: 0xff7a33, boss: 0xff2d55 });
 
+/**
+ * 活性源石 (infection) — the ONE palette of that tile, shared by the two boards (GitHub #184: the 2D atlas cell and the
+ * 3D shader used to be two different materials — a beveled brick with crystal clusters against a world-space crust).
+ * The values are the 3D board's own working colours (`render/board3d/materials.js` writes them into its shaders, which
+ * end in `#include <colorspace_fragment>`, i.e. they are LINEAR); `textures.js` converts them for its canvas with
+ * `linearToHex`, so both renderers show the same colour.
+ *   base — the crust's dark side, crust — its lit side, vein — the glowing veins, spec — the bright crystal grains.
+ */
+export const ORIGINIUM = Object.freeze({
+  base: Object.freeze([0.16, 0.05, 0.05]),
+  crust: Object.freeze([0.3, 0.1, 0.07]),
+  vein: Object.freeze([1.0, 0.46, 0.18]),
+  spec: Object.freeze([1.0, 0.78, 0.52]),
+  glow: 0xff6a3d,        // the additive pulse the 2D board tints per tile
+});
+
+/**
+ * One channel of a working (linear) colour as the 0–255 sRGB value a canvas stores — the shaders' `#include
+ * <colorspace_fragment>` does this for the 3D board, the canvas has to do it itself.
+ */
+export function linearToSrgb255(v) {
+  const k = Number(v);
+  const s = k <= 0.0031308 ? k * 12.92 : 1.055 * Math.pow(Math.max(0, k), 1 / 2.4) - 0.055;
+  return Math.max(0, Math.min(255, Math.round(s * 255)));
+}
+
+/** A working (linear) `ORIGINIUM` colour as the `#rrggbb` sRGB string of the canvas (`textures.js originiumCanvas`). */
+export function linearToHex(rgb) {
+  return `#${rgb.map((v) => linearToSrgb255(v).toString(16).padStart(2, '0')).join('')}`;
+}
+
 export const DMG_STYLE = Object.freeze({
   phys: { font: 'sp-dmg-phys', fill: ['#fffbe8', '#ffb35c'], stroke: '#3b1400' },
   arts: { font: 'sp-dmg-arts', fill: ['#fbe8ff', '#c77dff'], stroke: '#2a0b45' },