Add technical report, update docs/README, remove orphaned victory asset

- Add doc/AScreamFromTheDark_report.md: deep technical report covering
  architecture, features, historical workarounds and known debt.
- Rewrite README.md to reflect the current 'A Scream from the Dark'
  identity (ghost enemy, stamina/jump, fog of war, going-deeper victory)
  instead of the stale 'gioco carino' copy with old file paths.
- Update doc/generation.md: goal is now a random south-edge hatch,
  not the max-Manhattan-distance portal.
- Remove orphaned src/victory.{c,h} and its include in render.c;
  the victory sequence was replaced by the full-screen next_level image.
- Regenerate tracked png2asset outputs to match current build.

src/render.c

@@ -6,7 +6,6 @@
 #include "player.h"
 #include "enemy.h"
 #include "gameover.h"
-#include "victory.h"
 #include "stamina.h"
 #include "maze.h"