ci: split CI into separate macOS and Ubuntu workflows

- Add macOS.yml for macOS builds with Xcode 16
- Add ubuntu.yml for Ubuntu builds with Swift 6.0 container
- Remove old ci.yml workflow
- Update README badges to show separate platform status

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: 0xLeif

.github/workflows/ci.yml

@@ -0,0 +1,17 @@
+name: macOS
+
+on:
+  push:
+    branches: ["**"]
+
+jobs:
+  macOS:
+    runs-on: macos-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Select Xcode
+      run: sudo xcode-select -s /Applications/Xcode_16.0.app/Contents/Developer
+    - name: Build
+      run: swift build -v
+    - name: Run tests
+      run: swift test -v

.github/workflows/macOS.yml

@@ -0,0 +1,16 @@
+name: ubuntu
+
+on:
+  push:
+    branches: ["**"]
+
+jobs:
+  ubuntu:
+    runs-on: ubuntu-latest
+    container: swift:6.0
+    steps:
+    - uses: actions/checkout@v4
+    - name: Build
+      run: swift build -v
+    - name: Run tests
+      run: swift test -v

.github/workflows/ubuntu.yml

@@ -1,6 +1,7 @@
 # swift-algorand
 
-[![CI](https://img.shields.io/github/actions/workflow/status/CorvidLabs/swift-algorand/ci.yml?label=CI&branch=main)](https://github.com/CorvidLabs/swift-algorand/actions/workflows/ci.yml)
+[![macOS](https://img.shields.io/github/actions/workflow/status/CorvidLabs/swift-algorand/macOS.yml?label=macOS&branch=main)](https://github.com/CorvidLabs/swift-algorand/actions/workflows/macOS.yml)
+[![Ubuntu](https://img.shields.io/github/actions/workflow/status/CorvidLabs/swift-algorand/ubuntu.yml?label=Ubuntu&branch=main)](https://github.com/CorvidLabs/swift-algorand/actions/workflows/ubuntu.yml)
 [![License](https://img.shields.io/github/license/CorvidLabs/swift-algorand)](https://github.com/CorvidLabs/swift-algorand/blob/main/LICENSE)
 [![Version](https://img.shields.io/github/v/release/CorvidLabs/swift-algorand)](https://github.com/CorvidLabs/swift-algorand/releases)