fix(build): Restore SPM linkage for CI compatibility

Keep the normal Swift Package products using the explicit static linkage that existed before the binary distribution work. Xcode 15.4 CI still depends on that behavior when the iOS DemoApp build also builds the embedded watch app.

The XCFramework distribution continues to force dynamic frameworks through temporary distribution packages, so binary artifact generation remains separate from normal SPM linkage.

Refs EME-1168

Co-Authored-By: OpenAI Codex <noreply@openai.com>

Author: cameroncooke

Package.swift

@@ -10,25 +10,30 @@ let package = Package(
         // Products define the executables and libraries a package produces, making them visible to other packages.
         .library(
           name: "PreviewGallery",
+          type: .static,
           targets: ["PreviewGallery"]),
         // Test library to import in your XCTest target.
         // This is the only library that depends on XCTest.framework
         .library(
           name: "SnapshottingTests",
+          type: .static,
           targets: ["SnapshottingTests"]),
         // Link the main app to this target to use custom snapshot settings
         // This lib does not get inserted when running tests to avoid
         // duplicate symbols.
         .library(
           name: "SnapshotPreferences",
+          type: .static,
           targets: ["SnapshotPreferences"]),
         // Core functionality for snapshotting exported from the internal package
         .library(
           name: "SnapshotPreviewsCore",
+          type: .static,
           targets: ["SnapshotPreviewsCore"]),
         // Shared models required by the binary framework distribution.
         .library(
           name: "SnapshotSharedModels",
+          type: .static,
           targets: ["SnapshotSharedModels"]),
         // Dynamic library that your main app will have inserted to generate previews
         .library(