fix(doantu): retune calibration for phow2sim's wider cosine distribution

format.js was inherited from semantle (bge-m3 transformer) whose raw
cosines live in a narrow 0.4-0.55 band for unrelated words. phow2sim
runs on PhoW2V word2vec — related pairs sit at 0.3-0.5, synonyms at
0.55-0.80 — so the FLOOR=0.4 cutoff was dumping real signal (làng/đất
=0.38, làng/phố=0.38) to a displayed 0.

Retune: FLOOR=0.1, CENTER=0.4, SCALE=6. Now 0.38 → 39, 0.52 → 64, 0.80 → 93.

src/modules/doantu/README.md

@@ -43,8 +43,10 @@ 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 (identical
-  to semantle/format.js — score display is language-agnostic).
+- `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.
 - `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

@@ -1,12 +1,20 @@
 /**
  * @file Display formatting helpers for similarity scores.
- * Identical to semantle/format.js — score calibration is language-agnostic
- * because bge-m3 runs on both modules with the same cosine distribution.
+ *
+ * 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.
  */
 
-const FLOOR = 0.4;
-const CENTER = 0.6;
-const SCALE = 8.0;
+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));