Restructure PR detail: remove Commits tab, bottom icon tab bar, toolbar actions, markdown overview; bump to 1.9

- Remove the Commits tab (not useful).
- Move the section switcher to a bottom tab bar with icons (Overview /
  Conversation / Files / Checks) instead of a top segmented control.
- Move Review (menu) and Merge into the navigation toolbar, removing the
  bottom action bar.
- Add an Overview tab that renders the PR body as markdown via SwiftUI's
  built-in AttributedString(markdown:) (no third-party dependency).
- Bump to 1.9.

GiteaPR/Detail/Tabs.swift

@@ -142,28 +142,22 @@ struct FilesTab: View {
     }
 }
 
-// MARK: - Commits
+// MARK: - Overview
+
+/// Renders the PR body as markdown. Uses SwiftUI's built-in
+/// `AttributedString(markdown:)` so headings, bold, italic, links and inline
+/// code render without a third-party dependency.
+struct OverviewTab: View {
+    let pr: PullRequest
 
-struct CommitsTab: View {
-    let commits: [PRCommit]
     var body: some View {
-        VStack(alignment: .leading, spacing: 10) {
-            ForEach(commits) { commit in
-                HStack(alignment: .top, spacing: 10) {
-                    Text(commit.sha ?? commit.id)
-                        .font(.caption2.monospaced())
-                        .foregroundColor(.secondary)
-                        .frame(width: 60, alignment: .leading)
-                    VStack(alignment: .leading, spacing: 2) {
-                        Text(commit.commit?.message ?? "(no message)")
-                            .font(.callout)
-                            .lineLimit(3)
-                        Text(commit.author?.name ?? "")
-                            .font(.caption2)
-                            .foregroundColor(.secondary)
-                    }
-                }
-                Divider()
+        VStack(alignment: .leading, spacing: 12) {
+            if let body = pr.body, !body.isEmpty {
+                MarkdownText(body)
+            } else {
+                Text("No description.")
+                    .font(.callout)
+                    .foregroundColor(.secondary)
             }
         }
         .frame(maxWidth: .infinity, alignment: .leading)
@@ -171,6 +165,28 @@ struct CommitsTab: View {
     }
 }
 
+/// A Text view that renders a markdown string, falling back to plain text if
+/// the markdown can't be parsed.
+struct MarkdownText: View {
+    let markdown: String
+
+    init(_ markdown: String) {
+        self.markdown = markdown
+    }
+
+    var body: some View {
+        if let attributed = try? AttributedString(markdown: markdown) {
+            Text(attributed)
+                .font(.callout)
+                .frame(maxWidth: .infinity, alignment: .leading)
+        } else {
+            Text(markdown)
+                .font(.callout)
+                .frame(maxWidth: .infinity, alignment: .leading)
+        }
+    }
+}
+
 // MARK: - Checks
 
 struct ChecksTab: View {