Add Database and refactor player/playback

Add Database class with SQLite fetch/fetchAlbum methods. Refactor
PlaybackEngine (data callback, seek, getPosition, decoder lifecycle)
and Player API (PlaybackEngine member, queue handling, PlayerLocal).
Update Metadata::Track fields to include artist/title/album/trackNr/length.

include/PlaybackEngine.h

@@ -6,35 +6,39 @@
 #include <memory>
 
 struct PlaybackState {
-    ma_decoder decoder{};
-    std::atomic<bool> finished{ false };
+    ma_decoder decoder {};
+    std::atomic<bool> finished { false };
 };
 
 class PlaybackEngine {
-public:
-    PlaybackEngine();
-    ~PlaybackEngine();
+  public:
+    PlaybackEngine ();
+    ~PlaybackEngine ();
 
-    static void data_callback( ma_device* pDevice, void* pOutput, const void*, ma_uint32 frameCount );
-    void configureDevice();
-    void configureDecoder();
-    void initDevice();
-    void initDecoder( const char* filePath );
+    static void data_callback ( ma_device *pDevice, void *pOutput, const void *, ma_uint32 frameCount );
+    void configureDevice ();
+    void configureDecoder ();
+    void initDevice ();
+    void initDecoder ( const char *filePath );
+    void uninitDecoder();
 
-    void startPlayback();
-    void stopPlayback();
-    void pausePlayback() { stopPlayback(); };
-    int isFinished() const;
+    void startPlayback ();
+    void stopPlayback ();
+    void pausePlayback () { stopPlayback(); };
+    void seek ( ma_uint64 frame );
+    int isFinished () const;
 
-private:
+    ma_uint64 getPosition ();
 
+  private:
     ma_device device_;
     ma_format format_;
     unsigned int channels_;
     unsigned int sampleRate_;
     PlaybackState state;
 
-    //config
+    ma_uint64 cursor_;
+    // config
     ma_decoder_config decoderConfig;
     ma_device_config deviceConfig;
 };