Docs: bring GAME_DESIGN.md up to date, minor README consistency tweaks

GAME_DESIGN.md was ~100 commits behind: sphere brush with backface
rejection, spray, emission channel, camo/material sliders (runtime-only
persistence), radial pose menu + rendered pose icons, overview/escape
menu, rendering stack (HTrace WSGI / Deferred+, AVP shader URP ports,
lobby GI toggle), Poly Haven / ambientCG importers and misc editor
tools. README: radial pose menu + overview menu mentions.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -20,7 +20,8 @@ while hunters try to find them. Pure online PvP with an extended traversal kit
   camo sliders (brightness/saturation) and a **painting library** (save/load/delete
   named paintings, replicated to other players).
 - **Pose system** — poses (curl up, lie down, T-pose, …) to match object silhouettes,
-  with per-pose fall animations and rendered pose icons.
+  chosen via a radial menu with hotkeys, with per-pose fall animations and rendered
+  pose icons.
 - **Multiplayer (Netcode for GameObjects + UGS Sessions)** — session browser with
   host/join, lobby + match scenes, owner-authoritative movement sync, networked
   painting with late-join replay, role prefab variants (hunter/hider).
@@ -57,7 +58,7 @@ while hunters try to find them. Pure online PvP with an extended traversal kit
 | Left click | Paint (Paint mode) / shoot (hunter) |
 | Right click (hold) | Orbit camera in Paint mode |
 | E | Self-ping / taunt (hider, seek phase) |
-| Esc | Pause overlay / session browser |
+| Esc | Overview menu (pause, session browser, match results) |
 
 ## Getting started