GiteaPR: native iOS app to manage Gitea pull requests

Multi-repo PR inbox, review (approve/request changes/comment), merge with
gating toggle, read-only diff viewer, and Gitea Actions check status with
one-tap re-run. Ships unsigned via the iMac runner to the SideStore source.

GiteaPR/Detail/DiffView.swift

@@ -0,0 +1,79 @@
+import SwiftUI
+
+/// Read-only unified diff viewer for a single changed file.
+///
+/// Parses a Gitea unified diff patch into line hunks so added/deleted lines can
+/// be colour-coded. Gitea only returns `patch` for small diffs; large files
+/// fall back to a raw text view.
+struct DiffView: View {
+    let file: ChangedFile
+
+    var body: some View {
+        Group {
+            if let patch = file.patch, !patch.isEmpty {
+                ScrollView([.horizontal, .vertical]) {
+                    LazyVStack(alignment: .leading, spacing: 0) {
+                        ForEach(parse(patch)) { line in
+                            diffLine(line)
+                        }
+                    }
+                    .font(.caption.monospaced())
+                }
+            } else {
+                ContentUnavailableView(
+                    "Diff too large to preview",
+                    systemImage: "doc.text",
+                    description: Text("Gitea didn't return a patch for this file."))
+            }
+        }
+        .navigationTitle(file.filename)
+        .navigationBarTitleDisplayMode(.inline)
+    }
+
+    private func diffLine(_ line: DiffLine) -> some View {
+        Text(line.text)
+            .frame(maxWidth: .infinity, alignment: .leading)
+            .padding(.horizontal, 8)
+            .padding(.vertical, 1)
+            .background(background(for: line.type))
+            .foregroundColor(foreground(for: line.type))
+    }
+
+    private func background(for type: DiffLineType) -> Color {
+        switch type {
+        case .addition: return Color.green.opacity(0.15)
+        case .deletion: return Color.red.opacity(0.15)
+        case .hunk, .meta: return Color(.secondarySystemBackground)
+        case .context: return .clear
+        }
+    }
+    private func foreground(for type: DiffLineType) -> Color {
+        switch type {
+        case .addition: return .green
+        case .deletion: return .red
+        case .hunk: return .secondary
+        case .meta, .context: return .primary
+        }
+    }
+
+    private func parse(_ patch: String) -> [DiffLine] {
+        patch.components(separatedBy: "\n").map { line in
+            if line.hasPrefix("@@") { return DiffLine(text: line, type: .hunk) }
+            if line.hasPrefix("diff ") || line.hasPrefix("index ")
+                || line.hasPrefix("--- ") || line.hasPrefix("+++ ") {
+                return DiffLine(text: line, type: .meta)
+            }
+            if line.hasPrefix("+") { return DiffLine(text: line, type: .addition) }
+            if line.hasPrefix("-") { return DiffLine(text: line, type: .deletion) }
+            return DiffLine(text: line, type: .context)
+        }
+    }
+}
+
+private enum DiffLineType { case context, addition, deletion, hunk, meta }
+
+private struct DiffLine: Identifiable {
+    let text: String
+    let type: DiffLineType
+    var id: UUID { UUID() }
+}