refactor(doantu): drop sigmoid calibration — map raw cosine * 100

Sigmoid was inherited from semantle where bge-m3's narrow cone (unrelated
pairs at 0.40-0.55) needed spreading. phow2sim cosines span 0.0-0.8
naturally, so a linear map is honest and free of magic constants. Kept
the emoji buckets — they already work well against raw percentages.

src/modules/doantu/README.md

@@ -43,10 +43,11 @@ Override the base URL for local dev via `PHOW2SIM_API_URL`.
 - `state.js` — KV persistence for game + stats. Same shape as semantle.
 - `lookup.js` — guess normalization + shape validation. Accepts Unicode
   letters + combining marks + single internal spaces.
-- `format.js` — warmth-percent and emoji-bucket formatters. Calibration
-  constants differ from semantle/format.js: phow2sim (word2vec) has a
-  wider cosine distribution than bge-m3's narrow transformer cone, so
-  `FLOOR=0.1`, `CENTER=0.4`, `SCALE=6` here vs 0.4/0.6/8 there.
+- `format.js` — warmth-percent + emoji-bucket formatters. Linear
+  `round(raw * 100)` — phow2sim (word2vec) cosines already span a
+  game-friendly range (unrelated ~0.0, synonyms 0.6+), so no sigmoid
+  remap. Contrast with semantle/format.js which needs a sigmoid to
+  spread bge-m3's narrow transformer cone.
 - `render.js` — Telegram HTML `<pre>` monospace board with a 🇻🇳 header.
 - `handlers.js` — subject resolution + the three command entry points.
   Fast-path dedup (exact text OR prior canonical) skips wasted API calls

src/modules/doantu/format.js

@@ -1,32 +1,15 @@
 /**
  * @file Display formatting helpers for similarity scores.
  *
- * Tuned for phow2sim (PhoW2V word2vec): its cosine distribution is wider
- * than bge-m3's narrow transformer cone that semantle/format.js calibrates
- * against. Typical word2vec ranges:
- *   unrelated pairs:     0.00–0.15
- *   loosely related:     0.15–0.30
- *   clearly related:     0.30–0.55
- *   synonyms/same-topic: 0.55–0.80
- *   identical:           1.00
- * Mapping: raw 0.10 → 0, 0.30 → ~25, 0.40 → ~45, 0.50 → ~60, 0.70 → ~85, 1.00 → 100.
+ * phow2sim (PhoW2V word2vec) cosines already span a wide, game-friendly
+ * range — unrelated pairs near 0.0, synonyms 0.6+ — so we map linearly:
+ * `round(raw * 100)`, clamped to [0, 100]. Negative cosines (antonyms) clamp
+ * to 0. No sigmoid, no magic constants.
  */
 
-const FLOOR = 0.1;
-const CENTER = 0.4;
-const SCALE = 6.0;
-
-const sigmoid = (x) => 1 / (1 + Math.exp(-x));
-const FLOOR_SIG = sigmoid(SCALE * (FLOOR - CENTER));
-const ONE_SIG = sigmoid(SCALE * (1 - CENTER));
-const SIG_RANGE = ONE_SIG - FLOOR_SIG;
-
 /** @param {number} rawCosine */
 export function calibrate(rawCosine) {
-  if (rawCosine >= 1) return 100;
-  if (rawCosine <= FLOOR) return 0;
-  const s = sigmoid(SCALE * (rawCosine - CENTER));
-  return Math.max(0, Math.min(100, ((s - FLOOR_SIG) / SIG_RANGE) * 100));
+  return Math.max(0, Math.min(100, rawCosine * 100));
 }
 
 /** @param {number} score — calibrated score in [0, 100] */