feat: the apps' icons as one family, drawn by one tool (ADR 0031)

tool/app_icons.py at the root replaces Learn's and Todo's scripts: each
app's Lucide glyph (lucide-static 1.50.0) drawn by librsvg, fading from
cobalt through the colours ADR 0031 names, then every platform's
launcher icon through flutter_launcher_icons, Windows' .ico with every
size, and Learn's snap icon.

Learn's icon becomes the graduation cap, its window's on Linux too, with
Lucide's notice in its licence list; the kingfisher stays the emblem on
the rail and the launch screen. Todo's becomes list-todo, Train's bike.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/learn/tool/app_icons.py

@@ -1,85 +0,0 @@
-#!/usr/bin/env python3
-"""Makes the app's icons for every platform from its own, the kingfisher on white
-(halkyon_learn_flutter/assets/icon/halkyon_icon.png).
-
-- The snap's, snap/gui/halkyon-learn.png at the repository's root (512 x 512
-  pixels, the Snap Store's size), which the Store and the desktop file show as they
-  are: the picture with rounded corners, as other apps' white tiles have (radius
-  142.222 of 512, about 28 %).
-- Through flutter_launcher_icons, configured in the app's pubspec: Android's adaptive
-  icon and its older square one, iOS's, macOS's (the rounded tile on Apple's grid,
-  824 of 1024 pixels) and Windows' (the rounded tile).
-- Windows' .ico once more, with every size Windows shows (16 to 256 pixels): the tool
-  writes only the 256 one and leaves Windows to scale it down for its small views.
-- The iOS project file as it was: the tool sets every build setting with ASSETCATALOG
-  in its name to the icon set's name, Xcode's yes-or-no
-  ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS too, which breaks the
-  project (flutter_launcher_icons issue 634); the project names its icon set already.
-
-The derived images it hands to the tool go to halkyon_learn_flutter/build/icons/,
-which git ignores. The rounded corners' mask is drawn at four times the size and
-scaled down, so their edges are smooth.
-
-Run from apps/learn with Python 3 and Pillow (python3-pil on Ubuntu), the
-app's dependencies fetched:
-
-    python3 tool/app_icons.py
-"""
-
-import subprocess
-from pathlib import Path
-
-from PIL import Image, ImageDraw
-
-APP = Path("halkyon_learn_flutter")
-SOURCE = APP / "assets/icon/halkyon_icon.png"
-DERIVED = APP / "build/icons"
-SNAP_ICON = Path("../../snap/gui/halkyon-learn.png")
-WINDOWS_ICON = APP / "windows/runner/resources/app_icon.ico"
-IOS_PROJECT = APP / "ios/Runner.xcodeproj/project.pbxproj"
-RADIUS = 142.222 / 512
-SUPERSAMPLING = 4
-# Apple's grid: the tile is 824 of the icon's 1024 pixels, centred.
-MACOS_CANVAS = 1024
-MACOS_TILE = 824
-WINDOWS_SIZES = [16, 20, 24, 32, 40, 48, 64, 128, 256]
-
-
-def rounded(size: int) -> Image.Image:
-    """The icon at [size] pixels, its corners rounded off to transparency."""
-    icon = Image.open(SOURCE).convert("RGBA").resize((size, size), Image.LANCZOS)
-    large = size * SUPERSAMPLING
-    mask = Image.new("L", (large, large), 0)
-    ImageDraw.Draw(mask).rounded_rectangle(
-        (0, 0, large - 1, large - 1), radius=RADIUS * large, fill=255
-    )
-    mask = mask.resize((size, size), Image.LANCZOS)
-    # Keeps what the icon itself makes transparent, and takes the corners away.
-    transparent = Image.new("L", (size, size), 0)
-    icon.putalpha(Image.composite(icon.getchannel("A"), transparent, mask))
-    return icon
-
-
-def main() -> None:
-    rounded(512).save(SNAP_ICON, optimize=True)
-    print(f"Wrote {SNAP_ICON}.")
-
-    DERIVED.mkdir(parents=True, exist_ok=True)
-    rounded(1024).save(DERIVED / "rounded.png")
-    macos = Image.new("RGBA", (MACOS_CANVAS, MACOS_CANVAS), (0, 0, 0, 0))
-    margin = (MACOS_CANVAS - MACOS_TILE) // 2
-    macos.alpha_composite(rounded(MACOS_TILE), (margin, margin))
-    macos.save(DERIVED / "macos.png")
-
-    ios_project = IOS_PROJECT.read_bytes()
-    subprocess.run(["dart", "run", "flutter_launcher_icons"], cwd=APP, check=True)
-    IOS_PROJECT.write_bytes(ios_project)
-
-    rounded(256).save(
-        WINDOWS_ICON, format="ICO", sizes=[(size, size) for size in WINDOWS_SIZES]
-    )
-    print(f"Wrote {WINDOWS_ICON} with {len(WINDOWS_SIZES)} sizes.")
-
-
-if __name__ == "__main__":
-    main()