Overhauled the library with several new features (#5)

## Summary

Updates the library to v4.5.1 of the App Store Connect API, and ships it as a breaking 2.0.0 release with pagination, API key authentication, rate limiting, and a lighter install for consumers.

## Breaking changes

- **Minimum platforms:** iOS 14, macOS 11, tvOS 14, watchOS 7, and visionOS 1.
- **Toolchain:** Swift 6.0+ (Xcode 16+). The package builds in the Swift 6 language mode.
- **Runtime:** requires `swift-openapi-runtime` 1.11.0 or later.

## Changes

- **API:** updated the OpenAPI specification to v4.5.1, covering 1,303 operations and 1,473 schemas.
- **Pagination:** the spec patch adds the undocumented `cursor` query parameter to the 465 paged operations. `PagedDocumentLinks.nextCursor` reads the cursor from a page, and `PagedSequence` iterates every page.
- **Authentication:** `APIKeyTokenProvider` signs ES256 tokens from an API key and reuses each one until a minute before it expires. `BearerAuthMiddleware` now accepts a token provider.
- **Rate limiting:** `RateLimitMiddleware` retries `429` responses, waiting for `Retry-After` or backing off exponentially.
- **Generated code:** committed to `Sources/ASConnectService/Sources/Public/Generated` instead of generated by a build plugin. Consumers now resolve 4 packages instead of 12, and Xcode no longer asks to trust a plugin.
- **Tooling:**
  - `make oas-download` now downloads, patches, generates, and checks the docs in one go.
  - New `make oas-generate`, `make oas-validate`, and `make doc-check` targets.
  - The generator is pinned in `Tools/`, and the DocC plugin is only resolved by the documentation targets.
- **Documentation:** the DocC catalog now lists every operation and schema in the spec, and the catalog and README are rewritten for the new APIs.
- **Housekeeping:** Apache 2.0 license headers on every Swift file, including `Package.swift` and the tests.

Reviewed-on: #5
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>

Package.swift

@@ -1,27 +1,30 @@
-// swift-tools-version: 5.10
+// swift-tools-version: 6.0
 
-//===----------------------------------------------------------------------===
+// ===----------------------------------------------------------------------===
 //
 // This source file is part of the ASConnectService open source project
 //
 // Copyright (c) 2026 Röck+Cöde VoF. and the ASConnectService project authors
-// Licensed under the EUPL 1.2 or later.
+// Licensed under Apache license v2.0
 //
 // See LICENSE for license information
 // See CONTRIBUTORS for the list of ASConnectService project authors
 //
-//===----------------------------------------------------------------------===
+// SPDX-License-Identifier: Apache-2.0
+//
+// ===----------------------------------------------------------------------===
 
+import class Foundation.ProcessInfo
 import PackageDescription
 
 let package = Package(
     name: AppStoreConnectService.package,
     platforms: [
-        .iOS(.v13),
-        .macOS(.v10_15),
-        .tvOS(.v13),
+        .iOS(.v14),
+        .macOS(.v11),
+        .tvOS(.v14),
         .visionOS(.v1),
-        .watchOS(.v6)
+        .watchOS(.v7)
     ],
     products: [
         .library(
@@ -30,10 +33,9 @@ let package = Package(
         ),
     ],
     dependencies: [
-        .package(url: "https://github.com/apple/swift-openapi-generator.git", exact: "1.11.0"),
-        .package(url: "https://github.com/apple/swift-openapi-runtime", from: "1.5.0"),
-        .package(url: "https://github.com/apple/swift-openapi-urlsession", from: "1.0.2"),
-        .package(url: "https://github.com/swiftlang/swift-docc-plugin", from: "1.1.0")
+        // Must be at least the runtime version required by the generator in `Tools`.
+        .package(url: "https://github.com/apple/swift-openapi-runtime", from: "1.11.0"),
+        .package(url: "https://github.com/apple/swift-openapi-urlsession", from: "1.0.2")
     ],
     targets: [
         .target(
@@ -43,8 +45,9 @@ let package = Package(
                 .product(name: "OpenAPIURLSession", package: "swift-openapi-urlsession")
             ],
             path: "Sources/ASConnectService",
-            plugins: [
-                .plugin(name: "OpenAPIGenerator", package: "swift-openapi-generator")
+            exclude: [
+                "openapi.json",
+                "openapi-generator-config.yaml"
             ]
         ),
         .testTarget(
@@ -57,6 +60,13 @@ let package = Package(
     ]
 )
 
+// Only added by the documentation targets, so consumers don't resolve it.
+if ProcessInfo.processInfo.environment["ENABLE_DOCC_PLUGIN"] != nil {
+    package.dependencies.append(
+        .package(url: "https://github.com/swiftlang/swift-docc-plugin", from: "1.1.0")
+    )
+}
+
 // MARK: - Constants
 
 enum AppStoreConnectService {