docs: document the in-game stats HUD overlay

Author: savalet

docs/ARCHITECTURE.md

@@ -135,6 +135,13 @@ Each scene receives shared resources (`TextureManager`, `audioManager`,
 `NetworkManager`) instead of owning them, so assets and the connection
 persist across scene transitions.
 
+The in-game scene also owns a permanent [`Hud`](../gui/src/Scene/Hud.hpp)
+overlay rendered on top of the 3D view every frame: a top bar (solid-color
+panel via the `panel` shader + text via the `text` shader) displaying the map
+size, frequency, player/egg totals, per-team counts (color-coded), and the
+player-per-level distribution. It recomputes its strings from the `GameState`
+each frame and caches them to avoid rebuilding text geometry when unchanged.
+
 ### Networking & game state
 
 [`NetworkManager`](../gui/src/Network/NetworkManager.hpp) wraps an

docs/USAGE.md

@@ -48,6 +48,10 @@ that address/port **before** starting the GUI.
   menu, before connecting and entering the game view (see
   [`SceneManager`](../gui/src/SceneManager/SceneManager.hpp) for the full
   scene flow).
+- Once in the game view, a permanent **HUD bar** at the top of the window shows
+  live stats: map size, server frequency, total players, eggs, the player count
+  per team (color-coded), and the number of players at each level (1–8). See
+  [`Hud`](../gui/src/Scene/Hud.hpp).
 
 ## Running the bundled AI client