Implement NUFLI delta encoding with scanlines

- Add tools/apply_scanlines.py for CRT scanline effect
- Add tools/nufli_delta.py for delta encoding (base + bitmask deltas)
- Delta format: 2880 byte bitmask + N byte values per screen
- 40.1% size reduction vs raw NUFLI (69KB vs 115KB for 5 screens)
- Base (23KB) at 000-FFF, title delta (7KB) at -
- Other deltas use title as fallback (TODO: disk loading)
- Update tasks.md with scanline and delta encoding documentation

src/test_nufli.c

@@ -0,0 +1,17 @@
+#include "memmap.h"
+#include "nufli.h"
+#include <c64/vic.h>
+
+int main(void)
+{
+    memmap_setup();
+    
+    // Just try to access the NUFLI data
+    const unsigned char *data = nufli_get_screen(0);
+    
+    // Infinite loop
+    for (;;)
+        ;
+    
+    return 0;
+}