Add Periphery config and CI workflow; remove dead code

.github/workflows/periphery.yml

@@ -0,0 +1,21 @@
+name: Periphery
+on:
+  push:
+    branches: [main]
+  pull_request:
+jobs:
+  periphery:
+    name: Run Periphery
+    runs-on: macos-26
+    steps:
+      - uses: actions/checkout@v6
+      - uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: "26.4"
+      - uses: SwiftyLab/setup-swift@latest
+        with:
+          swift-version: "6.3"
+      - name: Install Periphery
+        run: brew install periphery
+      - name: Run Periphery
+        run: periphery scan

.periphery.yml

@@ -0,0 +1 @@
+retain_public: false

Sources/lib/GameFinder.swift

@@ -177,7 +177,6 @@ actor GameFinder {
     var fourtiles: [String]
 
     var count: Int { fourtiles.count }
-    var isEmpty: Bool { fourtiles.isEmpty }
 
     init(fourtiles: Set<String>) {
       self.fourtiles = Array(fourtiles)

Sources/lib/Games.swift

@@ -12,11 +12,6 @@ struct Game: Codable {
   /// All other words that can be formed by combinations of the tiles.
   let otherWords: Set<String>
 
-  /// The ``fourtiles`` and ``otherWords`` combined.
-  var words: Set<String> {
-    fourtiles.union(otherWords)
-  }
-
   func encode(to encoder: Encoder) throws {
     var container = encoder.container(keyedBy: CodingKeys.self)