Adopt Swift 6 language mode

Flip SWIFT_VERSION to 6.0 (keeping SWIFT_DEFAULT_ACTOR_ISOLATION = MainActor)
and resolve every resulting diagnostic. Mechanical, no behaviour change:

- Models: pure value types in Models/ and utility extensions (Date, DateFormatter,
  SRHTWebURL) marked nonisolated so the nonisolated networking layer can use them.
- App Intents: stored 'static var' (title/description/openAppWhenRun/
  typeDisplayRepresentation/defaultQuery/caseDisplayRepresentations) -> 'static let';
  drop the invalid @retroactive on the in-module LookupType: AppEnum.
- Sendable dicts: 'nil as String? as Any' -> 'nil as String? as any Sendable'.
- UserDefaults: retroactive @unchecked Sendable (documented thread-safe).
- WidgetKit completion handlers rebound nonisolated(unsafe) to cross into Task {};
  TipStoreViewModel task handle is @ObservationIgnored nonisolated(unsafe) for
  its nonisolated deinit.
- Tests run on @MainActor; a few constant fixtures marked nonisolated for use in
  @Sendable stub closures.

Builds and the full suite are clean in Swift 6 mode. Roadmap updated.

1 files changed, 6 insertions, 6 deletions

diff --git a/Hutch/Models/Patchset.swift b/Hutch/Models/Patchset.swift
index 330bbbc..cc10b35 100644
--- a/Hutch/Models/Patchset.swift
+++ b/Hutch/Models/Patchset.swift
@@ -1,7 +1,7 @@
 import Foundation
 
 /// Review state of a patchset on lists.sr.ht.
-enum PatchsetStatus: String, Codable, Sendable, CaseIterable {
+nonisolated enum PatchsetStatus: String, Codable, Sendable, CaseIterable {
     case unknown = "UNKNOWN"
     case proposed = "PROPOSED"
     case needsRevision = "NEEDS_REVISION"
@@ -55,7 +55,7 @@ enum PatchsetStatus: String, Codable, Sendable, CaseIterable {
 /// A patchset as it appears in a mailing list listing, derived from the thread's
 /// root email rather than a dedicated patchsets query — `MailingList` exposes no
 /// such field.
-struct PatchsetSummary: Identifiable, Hashable, Sendable {
+nonisolated struct PatchsetSummary: Identifiable, Hashable, Sendable {
     let id: Int
     let subject: String
     let version: Int
@@ -70,7 +70,7 @@ struct PatchsetSummary: Identifiable, Hashable, Sendable {
 }
 
 /// One email within a patchset: either the cover letter or a single patch.
-struct PatchsetEmail: Identifiable, Hashable, Sendable {
+nonisolated struct PatchsetEmail: Identifiable, Hashable, Sendable {
     let id: Int
     let subject: String
     let date: Date?
@@ -88,13 +88,13 @@ struct PatchsetEmail: Identifiable, Hashable, Sendable {
 }
 
 /// A build or check reported against a patchset.
-struct PatchsetToolResult: Identifiable, Hashable, Sendable {
+nonisolated struct PatchsetToolResult: Identifiable, Hashable, Sendable {
     let id: Int
     let icon: PatchsetToolIcon
     let details: String
 }
 
-enum PatchsetToolIcon: String, Codable, Sendable {
+nonisolated enum PatchsetToolIcon: String, Codable, Sendable {
     case pending = "PENDING"
     case waiting = "WAITING"
     case success = "SUCCESS"
@@ -112,7 +112,7 @@ enum PatchsetToolIcon: String, Codable, Sendable {
 }
 
 /// A patchset with its cover letter, patches, and review context.
-struct PatchsetDetail: Sendable {
+nonisolated struct PatchsetDetail: Sendable {
     let id: Int
     let created: Date
     let updated: Date