Fix 3D texture corruption and stuck/dead-key input bugs

Stale GL_UNPACK state in gl4es and a missing pre-release GPU sync
caused diagonal-banded corruption in the 3D view. Synthetic key
press/release must track the real controller button or touch down/up
edges, not fire together in one call - fixes a typed movement key
sticking forever, then a follow-up that had silently broken A-button
jump and on-screen keyboard arrow keys. Also adds force-rebuild.sh for
the known stageEngine stale-cache issue.

android/app/src/main/cpp/questshock_native.c

@@ -4,6 +4,7 @@
 // needs, compiled into the same "main" library as engine/ (see
 // android/engine-patches/01-android-shared-lib.patch's ANDROID_EXTRA_SOURCES)
 // - engine/ itself is never modified.
+#include <ctype.h>
 #include <jni.h>
 #include <unistd.h>
 
@@ -20,17 +21,30 @@ Java_de_ladkau_questshock_QuestShockActivity_nativeChdir(JNIEnv *env, jclass cla
 }
 
 // KeyboardOverlay's hand-built on-screen keyboard (see
-// KeyboardOverlay.commitPrintableChar()) has no real Android IME session
-// behind it, so printable characters can't reach the game via Android's
-// usual IME path - instead this builds and pushes an SDL_TEXTINPUT event
-// directly, the same event type/shape SDL's own Android backend pushes for
-// typed text, using only the public SDL_Event/SDL_PushEvent API. The
-// engine's pump_events() (sdl_events.c) only picks up printable characters
-// from this event, not from SDL_KEYDOWN (see handleKeyPress() in
-// KeyboardOverlay.java for why).
+// KeyboardOverlay.handleCharKeyDown()/handleCharKeyUp()) has no real
+// Android IME session behind it, so printable characters can't reach the
+// game via Android's usual IME path - instead this builds and pushes an
+// SDL_TEXTINPUT event directly, the same event type/shape SDL's own
+// Android backend pushes for typed text, using only the public
+// SDL_Event/SDL_PushEvent API. The engine's pump_events() (sdl_events.c)
+// only picks up printable characters from this event, not from
+// SDL_KEYDOWN.
+//
+// pump_events()'s SDL_TEXTINPUT handling sets sshockKeyStates[code] for
+// this character and only ever clears it again on a matching SDL_KEYUP.
+// Any character bound to a continuously-polled motion key (space -> jump,
+// w -> forward, etc., see MacSrc/Prefs.c's default keybinds.txt) is
+// polled every physics tick for as long as that state stays set, exactly
+// like a real held key - so nativeSendPrintableCharDown()/Up() are called
+// from the key button's own ACTION_DOWN/ACTION_UP (see
+// KeyboardOverlay.charKeyTouchListener()), not both at once: pushing the
+// release in the same call as the press would set and clear
+// sshockKeyStates[code] within a single pump_events() call, before the
+// game loop's poll (which runs once per frame, before pump_events - see
+// GameSrc/mainloop.c) ever has a chance to observe the press.
 JNIEXPORT void JNICALL
-Java_de_ladkau_questshock_KeyboardOverlay_nativeSendPrintableChar(JNIEnv *env, jclass clazz,
-                                                                   jchar c) {
+Java_de_ladkau_questshock_KeyboardOverlay_nativeSendPrintableCharDown(JNIEnv *env, jclass clazz,
+                                                                       jchar c) {
     SDL_Event event;
     SDL_zero(event);
     event.type = SDL_TEXTINPUT;
@@ -41,6 +55,23 @@ Java_de_ladkau_questshock_KeyboardOverlay_nativeSendPrintableChar(JNIEnv *env, j
     SDL_PushEvent(&event);
 }
 
+JNIEXPORT void JNICALL
+Java_de_ladkau_questshock_KeyboardOverlay_nativeSendPrintableCharUp(JNIEnv *env, jclass clazz,
+                                                                     jchar c) {
+    SDL_Event releaseEvent;
+    SDL_zero(releaseEvent);
+    releaseEvent.type = SDL_KEYUP;
+    releaseEvent.key.timestamp = SDL_GetTicks();
+    releaseEvent.key.windowID = 0;
+    releaseEvent.key.state = SDL_RELEASED;
+    releaseEvent.key.repeat = 0;
+    // SDL keycodes for printable characters are the character's own
+    // (lowercased) byte value - see sdl_events.c's own comment on this.
+    releaseEvent.key.keysym.sym = (SDL_Keycode)tolower((unsigned char)c);
+    releaseEvent.key.keysym.mod = KMOD_NONE;
+    SDL_PushEvent(&releaseEvent);
+}
+
 // KeyboardOverlay's title-bar Close button - the keyboard is a fully
 // independent overlay quad from the menu launcher (see xr_overlay.h), so
 // this is the only way to hide it once it's open; the controller's menu