added a state dumper for headless checks

src/ppu.rs

@@ -325,6 +325,20 @@ impl Ppu {
     pub fn framebuffer(&self) -> &[u8]   { &self.framebuffer }
     pub fn begin_frame(&mut self)        { self.frame_complete = false; self.scanline = 0; self.cycle = 0; }
 
+    // read-only accessors for the headless state dump
+    pub fn ctrl(&self) -> u8 { self.ctrl }
+    pub fn mask(&self) -> u8 { self.mask }
+    pub fn status(&self) -> u8 { self.status }
+    pub fn scanline(&self) -> u32 { self.scanline }
+    pub fn cycle(&self) -> u32 { self.cycle }
+    pub fn vram_addr(&self) -> u16 { self.vram_addr }
+    pub fn t(&self) -> u16 { self.t }
+    pub fn palette(&self) -> &[u8; 32] { &self.palette }
+    pub fn vram(&self) -> &[u8; 0x1000] { &self.vram }
+    pub fn framebuffer_nonzero(&self) -> usize {
+        self.framebuffer.iter().filter(|&&b| b != 0).count()
+    }
+
 
 
 }