chore: Halkyon Learn moves into apps/learn

Its server, client, app and curator, and the tools that write its
assets (maps, Anki fixtures, icons), as they are; paths are fixed in
the commits that follow.

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/halkyon_learn_flutter/ios/Runner/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -0,0 +1 @@
+{"images":[{"size":"20x20","idiom":"iphone","filename":"Icon-App-20x20@2x.png","scale":"2x"},{"size":"20x20","idiom":"iphone","filename":"Icon-App-20x20@3x.png","scale":"3x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@1x.png","scale":"1x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@2x.png","scale":"2x"},{"size":"29x29","idiom":"iphone","filename":"Icon-App-29x29@3x.png","scale":"3x"},{"size":"40x40","idiom":"iphone","filename":"Icon-App-40x40@2x.png","scale":"2x"},{"size":"40x40","idiom":"iphone","filename":"Icon-App-40x40@3x.png","scale":"3x"},{"size":"57x57","idiom":"iphone","filename":"Icon-App-57x57@1x.png","scale":"1x"},{"size":"57x57","idiom":"iphone","filename":"Icon-App-57x57@2x.png","scale":"2x"},{"size":"60x60","idiom":"iphone","filename":"Icon-App-60x60@2x.png","scale":"2x"},{"size":"60x60","idiom":"iphone","filename":"Icon-App-60x60@3x.png","scale":"3x"},{"size":"20x20","idiom":"ipad","filename":"Icon-App-20x20@1x.png","scale":"1x"},{"size":"20x20","idiom":"ipad","filename":"Icon-App-20x20@2x.png","scale":"2x"},{"size":"29x29","idiom":"ipad","filename":"Icon-App-29x29@1x.png","scale":"1x"},{"size":"29x29","idiom":"ipad","filename":"Icon-App-29x29@2x.png","scale":"2x"},{"size":"40x40","idiom":"ipad","filename":"Icon-App-40x40@1x.png","scale":"1x"},{"size":"40x40","idiom":"ipad","filename":"Icon-App-40x40@2x.png","scale":"2x"},{"size":"50x50","idiom":"ipad","filename":"Icon-App-50x50@1x.png","scale":"1x"},{"size":"50x50","idiom":"ipad","filename":"Icon-App-50x50@2x.png","scale":"2x"},{"size":"72x72","idiom":"ipad","filename":"Icon-App-72x72@1x.png","scale":"1x"},{"size":"72x72","idiom":"ipad","filename":"Icon-App-72x72@2x.png","scale":"2x"},{"size":"76x76","idiom":"ipad","filename":"Icon-App-76x76@1x.png","scale":"1x"},{"size":"76x76","idiom":"ipad","filename":"Icon-App-76x76@2x.png","scale":"2x"},{"size":"83.5x83.5","idiom":"ipad","filename":"Icon-App-83.5x83.5@2x.png","scale":"2x"},{"size":"1024x1024","idiom":"ios-marketing","filename":"Icon-App-1024x1024@1x.png","scale":"1x"}],"info":{"version":1,"author":"xcode"}}