Keep screen on during gameplay + ESP32 bridge design notes

GameScreen: add FLAG_KEEP_SCREEN_ON while a game is active. Keeps the
system out of the deeper sleep states that aggravate OTG selective-suspend
on Samsung, where the 8BitDo adapter otherwise drops every 60-120 seconds.
Cleared on dispose so other screens are unaffected.

docs: drop a design sketch for a DIY Joy-Con bridge built on an original
ESP32 or Raspberry Pi Pico W. Covers the two architectures (fully
wireless via BT Classic host + BLE peripheral, or wired hybrid via
BT Classic host + USB-CDC serial), the Joy-Con init subcommand
requirement, a proposed wire protocol for the serial path, and the
changes we'd make app-side to consume it. Also captures the dongle
rabbit hole we went through so future-us doesn't repeat the same
experiments.

Notes that Bluepad32 already implements BT Classic HID host with
first-class Joy-Con support on original ESP32 and Pico W, which
shrinks the firmware side considerably. Also warns explicitly against
ESP32-S3 for this project — despite being the obvious "newer, better"
ESP32, it is BLE-only and cannot pair with Joy-Cons (BR/EDR-only).

app/src/main/java/com/lazy/emulate/ui/screens/game/GameScreen.kt

@@ -1,5 +1,6 @@
 package com.lazy.emulate.ui.screens.game
 
+import android.app.Activity
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.os.Handler
@@ -7,6 +8,7 @@ import android.os.Looper
 import android.view.PixelCopy
 import android.view.SurfaceHolder
 import android.view.SurfaceView
+import android.view.WindowManager
 import androidx.compose.foundation.Image
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
@@ -109,6 +111,17 @@ fun GameScreen(
         ControllerLayout.defaultForConsole(game.consoleType)
     }
 
+    // Keep the screen on while a game is on-screen. This also keeps the system out of the
+    // deeper sleep / power-saving states that aggravate USB OTG selective-suspend on
+    // Samsung devices, where the adapter drops every ~60-120 seconds otherwise.
+    DisposableEffect(Unit) {
+        val window = (context as? Activity)?.window
+        window?.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
+        onDispose {
+            window?.clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
+        }
+    }
+
     DisposableEffect(game.id) {
         val loaded = EmulationEngine.startGame(context, game.consoleType, game.romPath)
         if (loaded != null) {