feat(editor): the dark scheme everywhere — the surface, documentation, mode buttons, program windows

The surface turns dark with light labels and cables and a faint light outline
round Java's icons; documentation rectangles become a tint of their colour and
texts are drawn towards light; the mode buttons use Java's pictures freed from
their grey ground (tools/dark-pictures/make.py); native controls follow
color-scheme; the desktop's program windows paint through Java-look tokens
whose light values are Java's own. The exported image and the report keep
Java's colours.

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

tools/dark-pictures/make.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+"""The mode buttons' pictures for the editor's dark scheme (packages/editor/src/assets/modes/*_dunkel.png).
+
+Java's pictures are 50 x 50 buttons: a frame and a vertical grey gradient (light blue and flat when the mode is
+on) around the icon. On a dark button that ground would stand as a light tile, so it is freed: the outer ring of
+RING pixels goes, and from there every pixel within GROUND of its row's ground colour (the gradient is row by row)
+becomes transparent, flooding inwards; a pixel up to EDGE from it (the icon's edge, blended with the grey) keeps its
+colour and fades with its likeness. Needs Pillow; run from the repository's root:
+
+    python3 tools/dark-pictures/make.py
+"""
+
+from collections import deque
+from pathlib import Path
+
+from PIL import Image
+
+MODES = Path(__file__).resolve().parents[2] / 'packages/editor/src/assets/modes'
+RING = 3
+GROUND = 8
+EDGE = 48
+
+
+def freed(picture: Image.Image) -> Image.Image:
+    image = picture.convert('RGBA')
+    width, height = image.size
+    pixels = image.load()
+    ground = [pixels[RING, y] for y in range(height)]
+    for y in range(RING):
+        ground[y] = ground[RING]
+    for y in range(height - RING, height):
+        ground[y] = ground[height - RING - 1]
+    seen = set()
+    queue = deque()
+    for x in range(width):
+        for y in range(height):
+            if x < RING or y < RING or x >= width - RING or y >= height - RING:
+                pixels[x, y] = (0, 0, 0, 0)
+                seen.add((x, y))
+                queue.extend([(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)])
+    while queue:
+        x, y = queue.popleft()
+        if (x, y) in seen or not (0 <= x < width and 0 <= y < height):
+            continue
+        seen.add((x, y))
+        colour = pixels[x, y]
+        distance = max(abs(colour[index] - ground[y][index]) for index in range(3))
+        if distance <= GROUND:
+            pixels[x, y] = (*colour[:3], 0)
+            queue.extend([(x + 1, y), (x - 1, y), (x, y + 1), (x, y - 1)])
+        elif distance <= EDGE:
+            pixels[x, y] = (*colour[:3], min(255, int(255 * (distance - GROUND) / (EDGE - GROUND))))
+    return image
+
+
+if __name__ == '__main__':
+    for source in sorted(MODES.glob('*.png')):
+        if source.stem.endswith('_dunkel'):
+            continue
+        freed(Image.open(source)).save(source.with_name(f'{source.stem}_dunkel.png'))
+        print(source.with_name(f'{source.stem}_dunkel.png').name)