Aggiunge traduzioni it/en/fr/de/es agli avvisi e toglie gli override Android/iOS.

Un avviso ha un testo per lingua; per differenziare le piattaforme si creano due avvisi. L'app riceve già il copy risolto da Accept-Language.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/spec/models/app_announcement_spec.rb

@@ -51,33 +51,22 @@ RSpec.describe AppAnnouncement do
     expect(described_class.for_app).to contain_exactly(android_item, ios_item)
   end
 
-  it "uses platform-specific copy and links when present" do
+  it "serves translated copy and falls back to English then Italian" do
     item = create_notice!(
-      title: "Comune",
-      body: "Testo comune",
-      action_url: "https://example.com/comune",
-      action_label: "Apri",
-      android_title: "Aggiorna su Android",
-      android_body: "Apri Play Store",
-      android_action_url: "https://play.google.com/store/apps/details?id=com.matchlivetv.match_live_tv",
-      android_action_label: "Play Store",
-      ios_title: "Aggiorna su iOS",
-      ios_body: "Apri App Store",
-      ios_action_url: "https://apps.apple.com/app/id000",
-      ios_action_label: "App Store"
+      title: "Titolo IT",
+      body: "Testo IT",
+      translations: {
+        "en" => { "title" => "EN title", "body" => "EN body" },
+        "de" => { "title" => "DE title", "body" => "DE body" }
+      }
     )
 
-    android = item.as_api_json(platform: "android")
-    ios = item.as_api_json(platform: "ios")
-
-    expect(android[:title]).to eq("Aggiorna su Android")
-    expect(android[:body]).to eq("Apri Play Store")
-    expect(android[:action_url]).to include("play.google.com")
-    expect(android[:action_label]).to eq("Play Store")
-    expect(ios[:title]).to eq("Aggiorna su iOS")
-    expect(ios[:body]).to eq("Apri App Store")
-    expect(ios[:action_url]).to include("apps.apple.com")
-    expect(ios[:action_label]).to eq("App Store")
+    expect(item.as_api_json(locale: :en)[:title]).to eq("EN title")
+    expect(item.as_api_json(locale: :de)[:title]).to eq("DE title")
+    expect(item.as_api_json(locale: :fr)[:title]).to eq("EN title")
+    expect(item.as_api_json(locale: :it)[:title]).to eq("Titolo IT")
+    expect(item.filled_locale_codes).to include("it", "en", "de")
+    expect(item.filled_locale_codes).not_to include("fr")
   end
 
   it "requires at least one channel" do