Add NES emulation support with bundled FCEUmm core

Implement NesCore with FCEUmm/Nestopia/Mesen libretro core support.
Generalize native frontend to handle cores that require ROM data in
memory (need_fullpath=false) and move PS1-specific config out of C++
into Ps1Core. Bundle both core .so files as APK assets with automatic
extraction. Fix cover art fetching for GoodNES-named ROMs by expanding
region codes (U)->(USA, Europe) to match LibRetro thumbnail naming.

app/src/main/cpp/jni_bridge.cpp

@@ -121,4 +121,18 @@ Java_com_lazy_emulate_emulation_NativeLibretro_nativeSetSaveDir(JNIEnv* env, job
     env->ReleaseStringUTFChars(dir, d);
 }
 
+JNIEXPORT void JNICALL
+Java_com_lazy_emulate_emulation_NativeLibretro_nativeSetControllerPortDevice(JNIEnv*, jobject, jint port, jint device) {
+    LibretroFrontend::instance().setControllerPortDevice(static_cast<unsigned>(port), static_cast<unsigned>(device));
+}
+
+JNIEXPORT void JNICALL
+Java_com_lazy_emulate_emulation_NativeLibretro_nativeSetCoreOption(JNIEnv* env, jobject, jstring key, jstring value) {
+    const char* k = env->GetStringUTFChars(key, nullptr);
+    const char* v = env->GetStringUTFChars(value, nullptr);
+    LibretroFrontend::instance().setCoreOption(k, v);
+    env->ReleaseStringUTFChars(value, v);
+    env->ReleaseStringUTFChars(key, k);
+}
+
 } // extern "C"

app/src/main/cpp/libretro_frontend.cpp

@@ -74,20 +74,14 @@ bool LibretroFrontend::loadCore(const char* soPath) {
     core_set_input_poll_(inputPollCallback);
     core_set_input_state_(inputStateCallback);
 
-    // Set controller to analog pad (DualShock) for PS1
-    core_set_controller_port_device_(0, RETRO_DEVICE_ANALOG);
-
     retro_system_info sys_info{};
     core_get_system_info_(&sys_info);
+    need_fullpath_ = sys_info.need_fullpath;
     LOGI("Core loaded: %s %s", sys_info.library_name, sys_info.library_version);
     LOGI("  need_fullpath: %d, block_extract: %d", sys_info.need_fullpath, sys_info.block_extract);
 
-    // Set default core options for pcsx_rearmed
-    core_options_["pcsx_rearmed_drc"] = "enabled";
-    core_options_["pcsx_rearmed_pad1type"] = "analog";
-    core_options_["pcsx_rearmed_frameskip_type"] = "disabled";
-    core_options_["pcsx_rearmed_region"] = "auto";
-    core_options_["pcsx_rearmed_memcard2"] = "disabled";
+    // Clear any previous core options
+    core_options_.clear();
 
     return true;
 }
@@ -100,13 +94,29 @@ bool LibretroFrontend::loadGame(const char* romPath) {
 
     LOGI("Loading game: %s", romPath);
 
-    // pcsx_rearmed uses need_fullpath=true, so we just pass the path
     retro_game_info game_info{};
     game_info.path = romPath;
-    game_info.data = nullptr;
-    game_info.size = 0;
     game_info.meta = nullptr;
 
+    if (need_fullpath_) {
+        game_info.data = nullptr;
+        game_info.size = 0;
+    } else {
+        // Core requires ROM data in memory
+        std::ifstream rom_file(romPath, std::ios::binary | std::ios::ate);
+        if (!rom_file) {
+            LOGE("Failed to open ROM file: %s", romPath);
+            return false;
+        }
+        size_t rom_size = rom_file.tellg();
+        rom_file.seekg(0);
+        rom_data_.resize(rom_size);
+        rom_file.read(reinterpret_cast<char*>(rom_data_.data()), rom_size);
+        game_info.data = rom_data_.data();
+        game_info.size = rom_size;
+        LOGI("ROM loaded into memory: %zu bytes", rom_size);
+    }
+
     if (!core_load_game_(&game_info)) {
         LOGE("retro_load_game failed");
         return false;
@@ -187,6 +197,8 @@ void LibretroFrontend::stop() {
         game_loaded_.store(false);
     }
 
+    rom_data_.clear();
+    rom_data_.shrink_to_fit();
     audio_engine_.stop();
     LOGI("Emulation stopped");
 }
@@ -641,12 +653,6 @@ void LibretroFrontend::setDisplayMode(int mode) {
 
 void LibretroFrontend::setFrameSkip(int skip) {
     frame_skip_ = skip;
-    if (skip > 0) {
-        core_options_["pcsx_rearmed_frameskip_type"] = "auto";
-        core_options_["pcsx_rearmed_frameskip_threshold"] = "33";
-    } else {
-        core_options_["pcsx_rearmed_frameskip_type"] = "disabled";
-    }
     options_updated_.store(true);
 }
 
@@ -657,3 +663,15 @@ void LibretroFrontend::setSystemDir(const char* dir) {
 void LibretroFrontend::setSaveDir(const char* dir) {
     save_dir_ = dir;
 }
+
+void LibretroFrontend::setControllerPortDevice(unsigned port, unsigned device) {
+    if (core_handle_ && core_set_controller_port_device_) {
+        core_set_controller_port_device_(port, device);
+        LOGI("Controller port %u set to device %u", port, device);
+    }
+}
+
+void LibretroFrontend::setCoreOption(const char* key, const char* value) {
+    core_options_[key] = value;
+    options_updated_.store(true);
+}

app/src/main/cpp/libretro_frontend.h

@@ -9,6 +9,7 @@
 #include <string>
 #include <thread>
 #include <unordered_map>
+#include <vector>
 
 enum class DisplayMode : int {
     STRETCH = 0,
@@ -43,6 +44,8 @@ public:
 
     void setSystemDir(const char* dir);
     void setSaveDir(const char* dir);
+    void setControllerPortDevice(unsigned port, unsigned device);
+    void setCoreOption(const char* key, const char* value);
 
     bool isRunning() const { return running_.load(); }
 
@@ -114,6 +117,10 @@ private:
     std::string system_dir_;
     std::string save_dir_;
 
+    // ROM data (kept alive for cores with need_fullpath=false)
+    std::vector<uint8_t> rom_data_;
+    bool need_fullpath_ = true;
+
     // Frame timing
     double target_fps_ = 60.0;
     int frame_skip_ = 0;