Preserve detail navigation origin (#66)

TESTING.md

@@ -247,9 +247,17 @@ source update are published, and installs or updates Gotcha through AltStore PAL
       first activity-feed page without requiring a manual pull-up; the empty
       state appears only after every available page has been checked.
 - [ ] Tap repository, issue, pull-request, and commit activity. Each opens the
-      matching native tab and destination.
+      matching destination on the Home navigation stack. The navigation-bar
+      Back button and left-edge interactive swipe return directly to Home.
 - [ ] Non-linkable server activity does not navigate or appear tappable.
 
+## Milestone navigation
+
+- [ ] Open a milestone, then open one of its issues and one of its pull
+      requests. For each detail, the navigation-bar Back button and left-edge
+      interactive swipe return directly to that milestone, preserving its
+      rows and scroll position.
+
 ## Home-screen widgets
 
 - [ ] Upgrade over a build with an existing server. Launch Gotcha once, then