Phase 3: move service layer, serializers and DTOs into WarpEngine + dummy-app test suite

- all catalog services (update/software/highlighted/builds/file/file-manager/
  download/image + SoftwareResponseBuilder), the SoftwareUpdater platform
  services and their concerns, Blueprinter serializers (incl. TimestampFields)
  and the 4 DTOs now live in the engine under WarpEngine::
- constantize dispatch strings use absolute names
  (WarpEngine::SoftwareUpdater::<Platform>Service)
- container paths read from WarpEngine.config everywhere (FileService,
  DownloadService, FileManagerService, ArchiveExtraction, ReleaseSerializer
  path rewriting); FileManagerService base path is now lazy
- engine requires blueprinter itself; gemspec declares blueprinter + rubyzip
- engine test suite: spec/dummy app (mysql warp_engine_test, catalog-only
  schema), rails_helper with engine-local factories; catalog model/service
  specs and factories moved from the host
- host suite keeps TTG specs and loads catalog factories from the engine

Verified: engine suite 40 green, host suite 14 green, /api/software and
/api/builds byte-identical to baselines, admin OK.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

spec/services/builds_service_spec.rb

@@ -0,0 +1,50 @@
+require "rails_helper"
+
+RSpec.describe WarpEngine::BuildsService do
+  describe "#index" do
+    subject(:result) { described_class.new.index }
+
+    it "returns all supported platforms with expected kinds" do
+      expect(result[:platforms]).to have_key("tic80")
+      expect(result[:platforms]["tic80"][:label]).to eq("TIC-80")
+      expect(result[:platforms]["tic80"][:kinds]).to include("cartridge", "html")
+    end
+
+    it "returns c64 with only cartridge" do
+      expect(result[:platforms]["c64"][:kinds]).to eq(["cartridge"])
+    end
+
+    it "returns allKinds matching WarpEngine::ReleaseAsset::KINDS" do
+      expect(result[:allKinds]).to eq(WarpEngine::ReleaseAsset::KINDS)
+    end
+
+    it "includes all supported platforms" do
+      WarpEngine::PlatformLink::SUPPORTED_PLATFORMS.each do |platform|
+        expect(result[:platforms]).to have_key(platform)
+      end
+    end
+  end
+
+  describe "#show" do
+    let!(:software) { create(:software, name: "test-game", platform: "love") }
+    let!(:release) { create(:release, software: software, version: "1.0.0") }
+
+    before do
+      WarpEngine::ReleaseAsset.create!(release: release, kind: "html", path: "/test/html")
+      WarpEngine::ReleaseAsset.create!(release: release, kind: "win_x64", path: "/test/win")
+    end
+
+    it "returns expected and actual kinds per release" do
+      result = described_class.new.show("test-game")
+
+      expect(result[:platform]).to eq("love")
+      expect(result[:expected]).to match_array(%w[html win_x64 linux_x64 mac_universal])
+      expect(result[:releases]["1.0.0"][:actual]).to match_array(%w[html win_x64])
+      expect(result[:releases]["1.0.0"][:missing]).to match_array(%w[linux_x64 mac_universal])
+    end
+
+    it "raises RecordNotFound for unknown software" do
+      expect { described_class.new.show("nonexistent") }.to raise_error(ActiveRecord::RecordNotFound)
+    end
+  end
+end