Several fixes and optimizations all over the library (#28)

This PR contains the work done to cleans up the library after the Swift 6.2 migration: drops the legacy conditional-compilation paths, hardens the OpenAPI specification, removes boilerplate from the live client, and makes the live test suite resilient to changes in the upstream service data.

* Swift 6.2 baseline
  * Adopted swift-tools-version: 6.2, which allowed removing every #if swift(>=6.0) / #if swift(>=6.2) branch and natural-language test names are now the only code paths.
  * `AmiiboClient` client now refines `Sendable`, and both `AmiiboLiveClient` and `AmiiboService` conform to it, so instances can be shared across concurrency domains.

* Live client
  * Extracted a generic `perform(_:)` helper that wraps every generated API call and funnels transport errors through the existing error mapper — replaces six repeated do/catch blocks and lets the private fetch* methods use typed throws end-to-end.
  * Added the internal `KeyNamePayload` protocol and a generic makeModels(from:), collapsing the four near-identical mapping/sorting blocks for amiibo series, types, game characters and game series into one.
  * The server URL is now resolved once into a static let constant instead of on every initialization.
  * Improved error mapping: URLError.cancelled → .cancelled, .cannotParseResponse → .decoding, and .dataNotAllowed, .internationalRoamingOff, .secureConnectionFailed now map to .notAvailable.
  * Simplified the Amiibo.Platform initializer ([Amiibo+Platform.swift](vscode-webview://1m6rk4uhpaukb4hrbp3j54p77iq693fq2ql7o9oup2pca1omf7f6/Sources/AmiiboService/Public/Models/Amiibo/Amiibo+Platform.swift)) using optional chaining and ?? [] instead of nested guards and immediately-invoked closures.
  * Set the en_US_POSIX locale on both fixed-format date formatters so the user's locale or 12/24-hour setting can no longer break parsing.

* OpenAPI specification
  * Replaced the shared Tuple schema with explicit per-type schemas (AmiiboSeries, AmiiboType, GameCharacter, GameSeries), so the generated code exposes real properties instead of allOf wrappers with .value1 accessors.
  * Extracted named list schemas (AmiiboList, AmiiboSeriesList, …) for the wrapper payloads, which turns the generated .case2 enum cases into readable .AmiiboSeriesList cases.
  * Added validation patterns and length bounds to the id, head, tail and key query parameters, and collapsed the redundant pattern/minLength/maxLength triplets on head/tail into ^[0-9a-fA-F]{8}$.
  * Extracted the shared InternalServerError response, replacing the five inline 500 descriptions.
  * Documented the two non-standard date/time decoding behaviours (date-only strings for release dates, offset-less timestamps for lastUpdated) and why the optional amiibo wrapper property must stay optional.
  * Corrected the info.version value from v1.0.0 to 1.0.0.

* ⚠️ Breaking changes
  *  Minimum Swift version raised from 5.10 to 6.2.
  *  `AmiiboServiceError.unknown` now carries a String description of the underlying error.
  *  `AmiiboClient` requires Sendable conformance, so existing custom mock clients must be Sendable.

Reviewed-on: #28
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Tests/AmiiboService/Helpers/Clients/AmiiboMockClient.swift

@@ -78,7 +78,6 @@ extension AmiiboMockClient: AmiiboClient {
     
     // MARK: Functions
 
-#if swift(>=6.0)
     func getAmiibos(
         by filter: AmiiboFilter
     ) async throws(AmiiboServiceError) -> [Amiibo] {
@@ -110,43 +109,8 @@ extension AmiiboMockClient: AmiiboClient {
     }
 
     func getLastUpdated() async throws(AmiiboServiceError) -> Date {
-        fetchLastUpdatedIfAny()
-    }
-#else
-    func getAmiibos(
-        by filter: AmiiboFilter
-    ) async throws -> [Amiibo] {
-        try fetchAmiibosIfAny()
-    }
-    
-    func getAmiiboSeries(
-        by filter: AmiiboSeriesFilter
-    ) async throws -> [AmiiboSeries] {
-        try fetchAmiiboSeriesIfAny()
-    }
-    
-    func getAmiiboTypes(
-        by filter: AmiiboTypeFilter
-    ) async throws -> [AmiiboType] {
-        try fetchAmiiboTypesIfAny()
-    }
-    
-    func getGameCharacters(
-        by filter: GameCharacterFilter
-    ) async throws -> [GameCharacter] {
-        try fetchGameCharactersIfAny()
-    }
-    
-    func getGameSeries(
-        by filter: GameSeriesFilter
-    ) async throws -> [GameSeries] {
-        try fetchGameSeriesIfAny()
-    }
-
-    func getLastUpdated() async throws -> Date {
         try fetchLastUpdatedIfAny()
     }
-#endif
     
 }
 
@@ -159,7 +123,7 @@ private extension AmiiboMockClient {
     /// Fetches a list of amiibo items, if any.
     /// - Returns: A list of amiibo items.
     /// - Throws: An ``AmiiboServiceError`` error in case an error has been provided.
-    func fetchAmiibosIfAny() throws -> [Amiibo] {
+    func fetchAmiibosIfAny() throws(AmiiboServiceError) -> [Amiibo] {
         try throwErrorIfExists()
         
         guard let amiibos else {
@@ -172,7 +136,7 @@ private extension AmiiboMockClient {
     /// Fetches a list of amiibo series, if any.
     /// - Returns: A list of amiibo series.
     /// - Throws: An ``AmiiboServiceError`` error in case an error has been provided.
-    func fetchAmiiboSeriesIfAny() throws -> [AmiiboSeries] {
+    func fetchAmiiboSeriesIfAny() throws(AmiiboServiceError) -> [AmiiboSeries] {
         try throwErrorIfExists()
         
         guard let amiiboSeries else {
@@ -185,7 +149,7 @@ private extension AmiiboMockClient {
     /// Fetches a list of amiibo types, if any.
     /// - Returns: A list of amiibo types.
     /// - Throws: An ``AmiiboServiceError`` error in case an error has been provided.
-    func fetchAmiiboTypesIfAny() throws -> [AmiiboType] {
+    func fetchAmiiboTypesIfAny() throws(AmiiboServiceError) -> [AmiiboType] {
         try throwErrorIfExists()
         
         guard let amiiboTypes else {
@@ -198,7 +162,7 @@ private extension AmiiboMockClient {
     /// Fetches a list of game characters, if any.
     /// - Returns: A list of game characters.
     /// - Throws: An ``AmiiboServiceError`` error in case an error has been provided.
-    func fetchGameCharactersIfAny() throws -> [GameCharacter] {
+    func fetchGameCharactersIfAny() throws(AmiiboServiceError) -> [GameCharacter] {
         try throwErrorIfExists()
         
         guard let gameCharacters else {
@@ -211,7 +175,7 @@ private extension AmiiboMockClient {
     /// Fetches a list of game series, if any.
     /// - Returns: A list of game series, if any.
     /// - Throws: An ``AmiiboServiceError`` error in case an error has been provided.
-    func fetchGameSeriesIfAny() throws -> [GameSeries] {
+    func fetchGameSeriesIfAny() throws(AmiiboServiceError) -> [GameSeries] {
         try throwErrorIfExists()
         
         guard let gameSeries else {
@@ -224,7 +188,7 @@ private extension AmiiboMockClient {
     /// Fetches a last updated date, if any.
     /// - Returns: A last updated date.
     /// - Throws: An ``AmiiboServiceError`` error in case an error has been provided.
-    func fetchLastUpdatedIfAny() throws -> Date {
+    func fetchLastUpdatedIfAny() throws(AmiiboServiceError) -> Date {
         try throwErrorIfExists()
         
         guard let lastUpdated else {