docs: record the HUD glyph quad decode in the backlog

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PMRJjbxLqZtsb5Vb7KunPE

docs/re/BACKLOG.md

@@ -319,6 +319,14 @@ is what the autopilot needs in order to CHOOSE a target. One run in:
   ACROPOLIS or the craft is lost — and a scan needs the run to survive **two**
   counter transitions. `frozen.in_flight()` at least makes a dead run say so
   immediately instead of waiting out its window.
+* ✅ **What the counter's neighbourhood IS — the HUD glyph quads**
+  (2026-08-24). The four pointers that move with it lead to objects whose vtable
+  is `0x820B2A64`: **32 slots**, methods `0x823c43b0…0x823c45a0`, **three**
+  construction sites in `sylpheed.db`. Each instance is a **textured quad** — a
+  pixel size (34×42 for a digit) and four vertices of `(colour, u, v)` — and the
+  UV rectangle × **1280×768** reproduces that pixel size to a rounding step, so
+  the font atlas size is measured, not guessed.
+  See [`structures/hud-glyph-quad.md`](structures/hud-glyph-quad.md).
 * 🔴 **The counter is not "hostiles left" either.** It held at `012` for fifteen
   minutes of live flight while the ADAN population fell 132 → 93.
 * ✅ **But it decrements when the player kills**: `12 → 11` with 411 `fire=1`