feat(zbugs-swift): an app icon that follows light and dark mode (#114)

The Zero logo from zero.rocicorp.dev, as an Icon Composer document for
iOS 26 and macOS 26: its dark mark on white in light mode, its light mark
on black in dark mode, and a white mark for tinted icons. An asset catalog
icon drawn on the old macOS grid was shrunk onto a grey plate in the
macOS 26 Dock; the .icon file takes the system's shape.

Amp-Thread-ID: https://ampcode.com/threads/T-c513a037-a257-45e0-b9a9-15c15edfe859

Co-authored-by: Amp <amp@ampcode.com>

Author: tmm

apps/zbugs-swift/App/AppIcon.icon/Assets/zero.svg

@@ -0,0 +1,61 @@
+{
+  "fill-specializations": [
+    {
+      "value": {
+        "solid": "srgb:1.00000,1.00000,1.00000,1.00000"
+      }
+    },
+    {
+      "appearance": "dark",
+      "value": {
+        "solid": "srgb:0.00000,0.00000,0.00000,1.00000"
+      }
+    },
+    {
+      "appearance": "tinted",
+      "value": {
+        "solid": "srgb:0.00000,0.00000,0.00000,1.00000"
+      }
+    }
+  ],
+  "groups": [
+    {
+      "layers": [
+        {
+          "fill-specializations": [
+            {
+              "value": {
+                "solid": "srgb:0.11765,0.11765,0.11765,1.00000"
+              }
+            },
+            {
+              "appearance": "dark",
+              "value": {
+                "solid": "srgb:0.88235,0.88235,0.88235,1.00000"
+              }
+            },
+            {
+              "appearance": "tinted",
+              "value": {
+                "solid": "srgb:1.00000,1.00000,1.00000,1.00000"
+              }
+            }
+          ],
+          "image-name": "zero.svg",
+          "name": "zero"
+        }
+      ],
+      "shadow": {
+        "kind": "neutral",
+        "opacity": 0.5
+      },
+      "translucency": {
+        "enabled": false,
+        "value": 0.5
+      }
+    }
+  ],
+  "supported-platforms": {
+    "squares": "shared"
+  }
+}

apps/zbugs-swift/App/AppIcon.icon/icon.json

@@ -18,6 +18,8 @@ targets:
       testTargets: [ZBugsUITests]
     sources:
       - path: ZBugsApp.swift
+      # The app icon (Icon Composer): the Zero logo from zero.rocicorp.dev.
+      - path: AppIcon.icon
       - path: Info.plist
         buildPhase: none
     dependencies:
@@ -32,6 +34,7 @@ targets:
         SWIFT_VERSION: '6.0'
         GENERATE_INFOPLIST_FILE: YES
         INFOPLIST_FILE: Info.plist
+        ASSETCATALOG_COMPILER_APPICON_NAME: AppIcon
         INFOPLIST_KEY_CFBundleDisplayName: Zero Bugs
         INFOPLIST_KEY_UILaunchScreen_Generation: YES
         INFOPLIST_KEY_UIApplicationSceneManifest_Generation: YES