Redraw toolbar icons: full-canvas copper ohm glyph, add generator

The previous 24 px icons were a copper square with a tiny knocked-out
ohm that was unreadable in the toolbar. tools/gen_icons.py renders the
glyph supersampled from DejaVu Sans Bold in theme-specific copper
shades (plus the 64 px PCM listing icon).

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

tools/gen_icons.py

@@ -0,0 +1,56 @@
+"""Generate the plugin icons: a bold copper Ω filling the canvas.
+
+    python tools/gen_icons.py
+
+Writes icons/fill_res_24_light.png (dark copper, for light toolbars),
+icons/fill_res_24_dark.png (bright copper, for dark toolbars) and
+resources/icon.png (64 px, for the PCM package listing). Rendered
+supersampled with matplotlib's bundled DejaVu Sans Bold, then
+downsampled for crisp antialiasing.
+"""
+from pathlib import Path
+
+import matplotlib
+from PIL import Image, ImageDraw, ImageFont
+
+SS = 20                                  # supersampling factor
+MARGIN = 1                               # px kept clear per 24 px
+
+COLORS = {
+    "light": (158, 88, 28),              # dark copper on light toolbar
+    "dark": (232, 162, 94),              # bright copper on dark toolbar
+}
+
+
+def render(color: tuple[int, int, int], size: int) -> Image.Image:
+    canvas = size * SS
+    img = Image.new("RGBA", (canvas, canvas), (0, 0, 0, 0))
+    draw = ImageDraw.Draw(img)
+    font_path = (Path(matplotlib.get_data_path())
+                 / "fonts" / "ttf" / "DejaVuSans-Bold.ttf")
+    # size the glyph so its ink box fills the canvas minus the margin
+    target = canvas - 2 * MARGIN * SS * size // 24
+    font = ImageFont.truetype(str(font_path), target)
+    x0, y0, x1, y1 = font.getbbox("Ω")
+    scale = min(target / (x1 - x0), target / (y1 - y0))
+    font = ImageFont.truetype(str(font_path), int(target * scale))
+    x0, y0, x1, y1 = font.getbbox("Ω")
+    pos = ((canvas - (x1 - x0)) // 2 - x0, (canvas - (y1 - y0)) // 2 - y0)
+    draw.text(pos, "Ω", font=font, fill=color + (255,))
+    return img.resize((size, size), Image.LANCZOS)
+
+
+def main() -> None:
+    root = Path(__file__).resolve().parent.parent
+    for theme, color in COLORS.items():
+        p = root / "icons" / f"fill_res_24_{theme}.png"
+        render(color, 24).save(p)
+        print(f"wrote {p}")
+    p = root / "resources" / "icon.png"
+    p.parent.mkdir(exist_ok=True)
+    render(COLORS["light"], 64).save(p)
+    print(f"wrote {p}")
+
+
+if __name__ == "__main__":
+    main()