Upgrade to OpenCV 5 with frozen Hershey templates and tighten video marks

- Lock OpenCV 5 and cap NumPy below 2.4 through uv constraint-dependencies so
  PaddleX 3.7 keeps resolving; Dependabot ignores mirror the cap.
- OpenCV 5 draws Hershey putText glyphs differently, so the Dola and Kling
  video templates ship as committed OpenCV 4 renders with a recipe script, and
  the OpenArt alpha recipe now refuses any OpenCV but 4.x.
- Break Sora/Veo cross-matches in favor of Veo under valid Google AI-video
  provenance, and require the full Sora mascot shape for mascot-only matches.
- Let the Doubao engine detect marks tinted by saturated backgrounds.
- Share C2PA claim-generator, credential-level and vendor-platform helpers,
  JPEG suffixes and the DCT basis instead of per-module copies.
- Log model download failures, document the optional GITHUB_TOKEN, mark the
  photo and source classifier model cards archived, and refresh the lock.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/render_video_hershey_templates.py

@@ -0,0 +1,78 @@
+"""Render the frozen OpenCV Hershey-font video templates for Dola and Kling.
+
+The video detectors were calibrated against these ``cv2.putText`` silhouettes as
+OpenCV 4.x draws them (byte-identical from 4.8 through 4.14). OpenCV 5 reworked
+text rendering, so the same call yields smaller, heavier glyphs, and the Dola
+gallery clip was then selected as Kling. The package therefore loads committed
+PNGs instead of rendering at import time; this script is the recipe that produced
+them. It refuses to run on any OpenCV other than 4.x.
+
+It also renders the independent Dola test fixture: the same text in the other
+Hershey face at a smaller scale, which tests/test_video.py stamps onto a frame to
+check that the detector is not keyed to its own template's exact pixels.
+
+Regenerate with:
+    uv run --no-project --with 'opencv-python-headless>=4.8,<5' --with numpy \
+        python scripts/render_video_hershey_templates.py
+"""
+
+from __future__ import annotations
+
+import logging
+from pathlib import Path
+
+import cv2
+import numpy as np
+
+log = logging.getLogger(__name__)
+
+_ROOT = Path(__file__).resolve().parents[1]
+_ASSETS = _ROOT / "src" / "remove_ai_watermarks" / "assets"
+_FIXTURES = _ROOT / "data" / "fixtures" / "synthetic"
+
+# Asset name -> (text, font, canvas width). Every template is drawn at scale 2.2,
+# thickness 3, anti-aliased, with the baseline origin at (2, 72) on a 100 px canvas.
+TEMPLATES = {
+    "video_dola_hershey_duplex.png": ("Dola AI", cv2.FONT_HERSHEY_DUPLEX, 400),
+    "video_kling_ai_hershey_simplex.png": ("KLING AI", cv2.FONT_HERSHEY_SIMPLEX, 500),
+    "video_kling_ai_hershey_duplex.png": ("KLING AI", cv2.FONT_HERSHEY_DUPLEX, 500),
+    "video_klingai_hershey_simplex.png": ("KlingAI", cv2.FONT_HERSHEY_SIMPLEX, 500),
+    "video_klingai_hershey_duplex.png": ("KlingAI", cv2.FONT_HERSHEY_DUPLEX, 500),
+}
+
+
+def render(
+    text: str,
+    font: int,
+    width: int,
+    *,
+    height: int = 100,
+    origin: tuple[int, int] = (2, 72),
+    scale: float = 2.2,
+    thickness: int = 3,
+) -> np.ndarray:
+    canvas = np.zeros((height, width), dtype=np.uint8)
+    cv2.putText(canvas, text, origin, font, scale, 255, thickness, cv2.LINE_AA)
+    ys, xs = np.nonzero(canvas)
+    return canvas[ys.min() : ys.max() + 1, xs.min() : xs.max() + 1]
+
+
+def _write(path: Path, image: np.ndarray) -> None:
+    if not cv2.imwrite(str(path), image):
+        raise SystemExit(f"failed to write {path}")
+    log.info("%s: %dx%d", path.relative_to(_ROOT), image.shape[1], image.shape[0])
+
+
+def main() -> None:
+    logging.basicConfig(level=logging.INFO, format="%(message)s")
+    if not cv2.__version__.startswith("4."):
+        raise SystemExit(f"OpenCV {cv2.__version__} draws different glyphs; run with OpenCV 4.x")
+    for name, (text, font, width) in TEMPLATES.items():
+        _write(_ASSETS / name, render(text, font, width))
+    fixture = render("Dola AI", cv2.FONT_HERSHEY_SIMPLEX, 150, height=40, origin=(2, 28), scale=0.9, thickness=2)
+    _FIXTURES.mkdir(parents=True, exist_ok=True)
+    _write(_FIXTURES / "dola_hershey_simplex.png", fixture)
+
+
+if __name__ == "__main__":
+    main()