Add a QuestShock startup splash; rename the app and data folder

AGENTS.md

@@ -16,7 +16,7 @@ a cross-platform port of the original engine, in an Android app that:
 - shows a menu and an on-screen keyboard as separate OpenXR quads, operated by
   a laser pointer from either controller;
 - maps controller inputs to game actions through a configurable binding layer;
-- persists settings in `/sdcard/questshock/questshock.config.json`.
+- persists settings in `/sdcard/QuestShock/questshock.config.json`.
 
 A desktop (Linux/Windows) build of the same engine exists for development
 without a headset; it has none of the Android/OpenXR code.
@@ -94,13 +94,14 @@ not print it or commit it.
 | `xr_input.c/.h` | Controller input: OpenXR actions, raw-input layer, action bindings, capture-mode rebinding, key injection into the engine, free view, cyberspace scaling, snap-turn/smooth-move of the player's position, pointer rays. The largest file. |
 | `xr_mouse.c/.h` | Injects mouse motion and clicks into the engine. |
 | `qs_config.c/.h` | Configuration: JSON parse, apply, write; screen profiles; menu-driven requests; cheats; menu-triggered pause. |
+| `qs_splash.c/.h` | Startup splash: `qs_splash_show()` fades the image (`res/splash.png`, decoded by Java and passed in through `nativeSetSplashImage`) in and out on the game screen. Called from engine patch 27. |
 | `questshock_native.c` | JNI exports and small native helpers (`nativeChdir`, `nativeSendPrintableChar`, ...). |
 
 ### 4.2 Java classes
 
 | Class | Role |
 |---|---|
-| `QuestShockActivity` | `SDLActivity` subclass. Creates `/sdcard/questshock/`, extracts bundled files, blocks engine start until the game data exists. |
+| `QuestShockActivity` | `SDLActivity` subclass. Creates `/sdcard/QuestShock/`, extracts bundled files, blocks engine start until the game data exists. |
 | `OverlayPanel` | Base for the off-screen panels: builds the view tree, renders it to a texture, turns ray hits into touch events. |
 | `MenuOverlay` | The menu: Main Menu, Video Options, Controller Options and Cheats tabs. Singleton. |
 | `KeyboardOverlay` | The on-screen keyboard. |
@@ -116,6 +117,10 @@ not print it or commit it.
   first-party code log under the tag `QuestShock`.
 - Bindings, config and menu state are owned natively. Java only displays and
   requests.
+- `gScreenWide`/`gScreenHigh` are only set by the engine's
+  `ChangeScreenSize()`, so they are 0 until its first mode change. Code that
+  runs during startup (such as `qs_splash_show()`) takes the screen size from
+  `xr_get_game_swapchain_size()` instead.
 
 ### 4.4 Threads and cross-thread requests
 
@@ -314,15 +319,19 @@ toggles.
 
 ## 10. Bundled files on the device
 
-`QuestShockActivity` extracts these into `/sdcard/questshock/`:
+`QuestShockActivity` extracts these into `/sdcard/QuestShock/`:
 
 - shaders, the default soundfont and `GET_ASSETS_QUEST.txt` (once);
 - `questshock.config.default.json` and `controller_profiles/` (every launch,
   overwriting only the bundled filenames so user-added profiles survive).
 
-`res/controller_profiles/` and the default config are staged into APK assets by
-`build-image/prepare-android-project.sh`; new staged directories must also be
-declared as `inputs.dir(...)` of `stageEngine` in `android/app/build.gradle`.
+`res/splash.png` stays in the APK assets and is not extracted to the device;
+`QuestShockActivity` decodes it and hands the pixels to `qs_splash.c`.
+
+`res/controller_profiles/`, `res/splash.png` and the default config are staged
+into APK assets by `build-image/prepare-android-project.sh`; every staged file
+or directory must also be declared as `inputs.file(...)`/`inputs.dir(...)` of
+`stageEngine` in `android/app/build.gradle`.
 
 The proprietary game data (`res/data/`, `res/sound/`) is never bundled or
 committed. The app refuses to start the engine until it is present.