Few fixes and improvements to the library, plus Github Actions setup (#31)

This PR contains the work done to fix a cancellation-mapping bug in `AmiiboLiveClient`, bring the client under offline test coverage, add the conformances SwiftUI and persistence need, and moves CI and documentation publishing to GitHub Actions. All public API changes are additive.

### Fix

- `AmiiboLiveClient` reported an early task cancellation as `.unknown("CancellationError()")`. The OpenAPI runtime wraps every error in `ClientError`, so the `CancellationError` check never matched; it now also checks the wrapped error and throws `.cancelled`.

### Tests

- `ThrowingTransport` and `StubTransport` test doubles let the live client run offline. New tests cover error mapping, HTTP status → error mapping, `oneOf` object-vs-list decoding, `"amiibo": null`, sorting, filter → query encoding, `Platform`/`Release` mapping, and the date transcoder.
- Models gained `package` memberwise initializers so tests can build real fixtures without `@testable`. These are not public API.
- The test target now depends on `OpenAPIRuntime` and `HTTPTypes` (both already in the dependency graph).

### API
- Models are `Codable` and `Identifiable` (`Amiibo.id` is its `identifier`; the key/name models use `key`).
- Filters are `Hashable`.

### Documentation
- Doc comments trimmed library-wide; one repeated `- Throws:` sentence appeared 24 times. `Library.md` and the README tightened to match.

### CI and docs publishing
- `ci.yml`: build and offline tests on PRs and pushes to `main`.
- `live-tests.yml`: weekly and on-demand run against the live API.
- `docs.yml`: builds DocC on PRs, deploys to GitHub Pages on `main`. Pinned to Xcode 26 because swift-docc-plugin 1.5.0 fails to launch its tools under Xcode 27.
- The generated `docs/` folder (327 files) is removed from the repository and ignored.

Reviewed-on: #31
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>

Sources/AmiiboService/Internal/Transcoders/ISODateTimeTranscoder.swift

@@ -15,15 +15,15 @@
 import Foundation
 import OpenAPIRuntime
 
-/// A type that allows the decoding and encoding of ISO dates, supporting both the `yyyy-MM-dd'T'HH:mm:ss.SSSSSS` timestamp format and the `yyyy-MM-dd` date-only format.
+/// A transcoder for ISO dates in the `yyyy-MM-dd'T'HH:mm:ss.SSSSSS` timestamp and `yyyy-MM-dd` date-only formats.
 struct ISODateTimeTranscoder {
     
     // MARK: Properties
     
-    /// A formatter to use to decode and encode ISO timestamp dates.
+    /// The ISO timestamp formatter.
     private let timestampFormatter: DateFormatter = .isoTimestamp
-    
-    /// A formatter to use to decode and encode ISO date-only strings.
+
+    /// The ISO date-only formatter.
     private let dateFormatter: DateFormatter = .isoDate
     
 }
@@ -34,17 +34,13 @@ extension ISODateTimeTranscoder: DateTranscoder {
     
     // MARK: Functions
     
-    /// Encodes a date into an ISO timestamp string.
-    /// - Parameter date: A date to encode.
-    /// - Returns: A string representation of the date in `yyyy-MM-dd'T'HH:mm:ss.SSSSSS` format.
+    /// Encodes a date as an ISO timestamp string.
     func encode(_ date: Date) throws -> String {
         timestampFormatter.string(from: date)
     }
     
-    /// Decodes an ISO date string into a date, trying the timestamp format first and falling back to the date-only format.
-    /// - Parameter string: A string to decode.
-    /// - Returns: A date parsed from the string.
-    /// - Throws: A `DecodingError` if the string cannot be parsed into a valid date.
+    /// Decodes an ISO date string, trying the timestamp format before the date-only one.
+    /// - Throws: A `DecodingError` if the string matches neither format.
     func decode(_ string: String) throws -> Date {
         if let date = timestampFormatter.date(from: string) {
             return date