remove dead code: core/images.py

make_thumbnail and image_dimensions were both unreferenced. The
library's actual thumbnailing happens inline in gui/library.py
(PIL for stills, ffmpeg subprocess for videos), and the live
image_dimensions used by main_window.py is the static method on
gui/media_controller.py — not the standalone function this file
exposed. Audit finding #15 follow-up.

booru_viewer/core/images.py

@@ -1,31 +0,0 @@
-"""Image thumbnailing and format helpers."""
-
-from __future__ import annotations
-
-from pathlib import Path
-
-from PIL import Image
-
-from .config import DEFAULT_THUMBNAIL_SIZE, thumbnails_dir
-
-
-def make_thumbnail(
-    source: Path,
-    size: tuple[int, int] = DEFAULT_THUMBNAIL_SIZE,
-    dest: Path | None = None,
-) -> Path:
-    """Create a thumbnail, returning its path. Returns existing if already made."""
-    dest = dest or thumbnails_dir() / f"thumb_{source.stem}_{size[0]}x{size[1]}.jpg"
-    if dest.exists():
-        return dest
-    with Image.open(source) as img:
-        img.thumbnail(size, Image.Resampling.LANCZOS)
-        if img.mode in ("RGBA", "P"):
-            img = img.convert("RGB")
-        img.save(dest, "JPEG", quality=85)
-    return dest
-
-
-def image_dimensions(path: Path) -> tuple[int, int]:
-    with Image.open(path) as img:
-        return img.size