Boot-Sequenz vermessen + Intro-Player gebaut, echten PCC-Decoder-Regressionsbug gefixt

- Regression gefunden+gefixt: pcc_to_png.py war durch einen frueheren Commit
  versehentlich auf den kaputten Hand-RLE-Decoder zurueckgefallen (der
  ImageMagick-Fix ging verloren). Jetzt: kellogg_formats.load_pcc() nutzt
  Pillows PCX-Decoder direkt, kein eigener RLE-Code mehr im Projekt. Alle
  77 PCC neu gerendert, AE=0 (pixelidentisch) zu den alten guten PNGs.
- Boot-Sequenz per echter DOSBox-Screenshot-Serie (0.3s-Intervall) vermessen:
  Rauser-Karte -> Factor5-Logo (statisch, keine Animation) -> Kellogg's-Logo
  mit Palette-Fade des "praesentiert"-Texts (Indizes 34/42/43/44/45) ->
  Titelbild "Tony & Friends in Kellogg's Land" mit echtem Vorhang-Wipe-Effekt
  (320x480 aus 4 Quadranten KELL256A-D, obere Haelfte faehrt runter, untere
  hoch, treffen sich in der Mitte). Korrigiert eine fruehere Fehlannahme:
  der Wipe sitzt auf dem TITELBILD, nicht auf dem Kellogg's-Markenlogo.
- tools/intro_sequence.py: erster spielbarer pygame-Meilenstein, baut die
  komplette Sequenz nach (Asset-Loading, Palette-Rendering, Timing, echter
  Palette-Fade, Wipe-Effekt). Headless getestet, visuell verifiziert.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tools/kellogg_formats.py

@@ -61,6 +61,47 @@ def get_pcx_palette(pcc_bytes):
     return [tuple(pal_bytes[i:i+3]) for i in range(0, 768, 3)]
 
 
+def load_pcc(pcc_bytes):
+    '''Decode a .PCC (= plain PCX v5, 8bpp, RLE, own trailing 256-color
+    palette) via Pillow's battle-tested PCX decoder instead of a hand-rolled
+    RLE parser -- see git history 2026-07-22 (commits 5efba4b/62af15e/3410a53)
+    for why: TWO from-scratch RLE implementations silently produced visibly
+    wrong pixels (shifted/duplicated content) for full-screen 320x200 images
+    (KARTE.PCC, KELLOGGS.PCC) despite being "verified" -- Pillow avoids that
+    whole class of bug entirely.
+
+    Returns (width, height, indices, palette):
+      indices  -- flat list[int] of palette indices, len width*height, row-major
+      palette  -- list of 256 (r,g,b) tuples (this file's OWN embedded palette,
+                  not any global one)
+    '''
+    from PIL import Image
+    import io
+    img = Image.open(io.BytesIO(pcc_bytes))
+    img.load()
+    if img.mode != 'P':
+        raise ValueError(f'expected palette (P) mode PCX, got {img.mode}')
+    width, height = img.size
+    indices = list(img.getdata())
+    raw_pal = img.getpalette()  # flat [r,g,b, r,g,b, ...], may be shorter than 768
+    raw_pal = (raw_pal + [0] * 768)[:768]
+    palette = [tuple(raw_pal[i:i+3]) for i in range(0, 768, 3)]
+    return width, height, indices, palette
+
+
+def pcc_to_rgba(pcc_bytes, transparent_index=None):
+    '''Convenience wrapper around load_pcc(): returns (width, height, rgba_bytes)
+    ready for e.g. pygame.image.frombuffer(rgba, (w,h), 'RGBA') or PIL Image.frombytes.
+    If transparent_index is given, that palette index becomes alpha=0.'''
+    width, height, indices, palette = load_pcc(pcc_bytes)
+    out = bytearray(width * height * 4)
+    for i, idx in enumerate(indices):
+        r, g, b = palette[idx & 0xFF]
+        a = 0 if (transparent_index is not None and idx == transparent_index) else 255
+        out[i*4:i*4+4] = bytes([r, g, b, a])
+    return width, height, bytes(out)
+
+
 def get_bob_palette(entries, name):
     '''name = basename without extension, e.g. 'TONY' for TONY.BOB.
     Implements the palette-selection rules from Form1.cs (BOB case).'''