Add configurable game/initial screen width and distance, with a bundled first-run config

- Video Options tab offers width and distance presets independently for
  the Initial Screen (splash/intro/menu) and Game Screen (gameplay)
  profiles, with their preset step/offset configurable via
  questshock.config.json.
- Ships res/questshock.config.default.json as the initial config on
  first run (or whenever questshock.config.json doesn't exist yet),
  refreshed from the APK on every launch without touching a user's own
  saved config.

android/app/src/main/cpp/qs_config.h

@@ -66,15 +66,42 @@ void qs_config_request_set_language(int language_index);
 // player's current real head pose instead.
 void qs_config_request_reset_position(void);
 
-// Returns true and handles the event if it's one of the six custom events
+// Same cross-thread-dispatch reasoning as the four above - called from the
+// Video Options tab's "Initial Screen"/"Game Screen" width/distance
+// preset rows (MenuOverlay.java). preset_index indexes qs_config.c's own
+// shared, offset+step-generated width/distance preset lists (both in
+// meters; the offset/step themselves are config-file-only, not exposed
+// as buttons), read back via the four qs_config_current_*_screen_*_index()
+// getters below. Applies live immediately if the just-changed profile is
+// the currently active one (see CONFIG.md) - otherwise just updates the
+// stored preference, invisibly, until that profile becomes active (e.g.
+// tweaking "Initial Screen" mid-game).
+void qs_config_request_set_initial_screen_width(int preset_index);
+void qs_config_request_set_initial_screen_distance(int preset_index);
+void qs_config_request_set_game_screen_width(int preset_index);
+void qs_config_request_set_game_screen_distance(int preset_index);
+
+// Returns true and handles the event if it's one of the ten custom events
 // qs_config_request_save()/_load()/_set_renderer()/_set_resolution()/
-// _set_language()/_reset_position() enqueue - called from pump_events()
-// (sdl_events.c, see android/engine-patches/21-android-config.patch) on the
-// engine's own thread, once per polled event, before its normal switch on
-// well-known SDL_* event types. Returns false (no-op) for any other event
-// type, including before the six custom types have even been registered.
+// _set_language()/_reset_position()/the four _set_*_screen_*() setters
+// enqueue - called from pump_events() (sdl_events.c, see
+// android/engine-patches/21-android-config.patch) on the engine's own
+// thread, once per polled event, before its normal switch on well-known
+// SDL_* event types. Returns false (no-op) for any other event type,
+// including before the ten custom types have even been registered.
 bool qs_config_handle_event(const SDL_Event *event);
 
+// Called directly (no event-queue dispatch - see
+// android/engine-patches/22-android-screen-profile.patch and this
+// function's own definition in qs_config.c for why) from the engine's
+// mainloop.c whenever the loop mode changes, and once from
+// qs_config_load_startup() - picks between the "Initial Screen" (menu/
+// intro) and "Game Screen" (actual gameplay) presets based on new_mode
+// (mainloop.h's SETUP_LOOP/CUTSCENE_LOOP vs. everything else) and applies
+// the newly-active one's shape to xr_session.c, but only if it's actually
+// different from what was already active.
+void qs_screen_profile_notify_loop_mode(short new_mode);
+
 // Read-only queries for the Video Options tab's own selection highlight
 // (MenuOverlay.java re-reads these whenever the tab is (re)shown, so it
 // reflects the live value even if it was last changed some other way, e.g.
@@ -87,6 +114,28 @@ bool qs_config_handle_event(const SDL_Event *event);
 bool qs_config_current_renderer_is_opengl(void);
 int qs_config_current_resolution_index(void);
 
+// -1 (not just an unlikely fallback, a routine, expected result here -
+// unlike qs_config_current_resolution_index() above) if the profile's
+// current value doesn't exactly match one of qs_config.c's own
+// offset+step-generated width/distance presets, e.g. after a hand-edited
+// config file sets an in-between value - MenuOverlay.java's own
+// setSelected() naturally shows no button selected in that case, no
+// special-casing needed.
+int qs_config_current_initial_screen_width_index(void);
+int qs_config_current_initial_screen_distance_index(void);
+int qs_config_current_game_screen_width_index(void);
+int qs_config_current_game_screen_distance_index(void);
+
+// Returns the value preset button `index` (0..4) currently shows for the
+// width/distance option - shared by both "Initial Screen" and "Game
+// Screen" columns (their offset/step is config-file-only, not per-profile
+// - see qs_config.c's own comment on the underlying statics), so
+// MenuOverlay.java can label its preset buttons correctly even after a
+// Load Configuration changes the offset/step. Index is clamped into
+// range, not validated - every index 0..4 always has a value.
+float qs_config_screen_width_preset_value(int index);
+float qs_config_screen_distance_preset_value(int index);
+
 // gShockPrefs.goLanguage (0 English/1 French/2 German, Prefs.h) - read by
 // MenuOverlay.java's/KeyboardOverlay.java's periodic header-refresh timer
 // to pick which language's chrome text (Strings.java) to display, so a