feat: review patchsets

Patchsets are how contributions reach sourcehut, and Hutch had no reference to
them anywhere. This adds review and triage: read a series, see its checks and
version chain, and set its status.

Two schema facts shaped the design.

MailingList exposes no patchsets field, so a list's patchsets cannot be queried
directly. They are reachable only through thread roots, so the existing threads
query now also selects root.patchset — no extra request — and the Patches tab is
derived from that. It appears only on lists that actually carry patches.

Patch carries no diff. index, count, version, prefix, subject, and trailers are
all it has; the diff exists only inside the email body. Patch bodies are split
with the same InboxThreadUtilities.segmentMessageBody the inbox uses and
rendered through the existing DiffView.

Patches are ordered by their [PATCH n/m] index rather than receipt order, since
mail arrives out of sequence. Patches with no index are kept at the end rather
than dropped, because a one-off patch has no prefix.

updatePatchset is nullable, so a null response is treated as a declined change
and the local status is left alone rather than advanced optimistically. UNKNOWN
and SUPERSEDED are not offered: the first is a sentinel, the second is set by
the server when a newer version lands.

Patch submission stays out of scope. It is a git send-email flow, not a GraphQL
mutation.

1 files changed, 3 insertions, 0 deletions

diff --git a/Hutch/App/RootView.swift b/Hutch/App/RootView.swift
index 1ae4651..59d7caa 100644
--- a/Hutch/App/RootView.swift
+++ b/Hutch/App/RootView.swift
@@ -439,6 +439,7 @@ enum MoreRoute: Hashable {
     case projectDashboard(id: String, title: String?)
     case mailingList(InboxMailingListReference)
     case thread(InboxThreadSummary)
+    case patchset(id: Int, listName: String?)
     case manPageBrowser
     case manPage(URL)
 }
@@ -472,6 +473,8 @@ private struct MoreNavigationRoot: View {
                     ProjectDashboardDeepLinkView(projectID: id, title: title)
                 case .mailingList(let mailingList):
                     MailingListDetailView(mailingList: mailingList)
+                case .patchset(let id, let listName):
+                    PatchsetDetailView(patchsetID: id, listName: listName)
                 case .thread(let thread):
                     ThreadDetailView(
                         thread: thread,