feat(clients): in-app OSS / third-party-license screens

Surface THIRD-PARTY-NOTICES.txt in every GUI client (the desktop packages already
ship it as a file; this adds the on-glass screen):

- Linux: Preferences -> About -> Third-party licenses (adw::AboutDialog with the app
  license + Legal sections; include_str! the root notices).
- Apple: macOS About tab / iOS+tvOS Acknowledgements link; notices bundled as
  PunktfunkKit SPM resources, read via Bundle.module (the Xcode app links the SPM
  product, so they ride along - no .pbxproj edit).
- Android: Settings -> About -> Open-source licenses (reads the bundled asset).
- (Windows landed earlier in d1d2ca2: Settings -> About -> Third-party licenses.)

gen-third-party-notices.sh now copies the generated file into the Apple Resources/
and Android assets/ trees so the in-tree copies never drift.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/apple/Package.swift

@@ -16,6 +16,15 @@ let package = Package(
         .target(
             name: "PunktfunkKit",
             dependencies: ["PunktfunkCore"],
+            // OSS attribution shown by the app's Acknowledgements screen. Bundled here (not in the
+            // app target) so it rides along via Bundle.module in both `swift build` and the Xcode
+            // app, which links the PunktfunkKit product. Refresh with
+            // scripts/gen-third-party-notices.sh (it copies the generated file into Resources/).
+            resources: [
+                .copy("Resources/THIRD-PARTY-NOTICES.txt"),
+                .copy("Resources/LICENSE-MIT.txt"),
+                .copy("Resources/LICENSE-APACHE.txt"),
+            ],
             linkerSettings: [
                 // Rust staticlib system deps.
                 .linkedFramework("Security"),