Render descriptions with shared Markdown preview

Use one Markdown presentation for free-form content.

- issue and pull-request descriptions and comments
- milestone and commit descriptions

TESTING.md

@@ -192,6 +192,10 @@ xcrun simctl launch booted de.rfc1437.gotcha
       Multiple labels wrap without clipping at large Dynamic Type sizes and
       VoiceOver announces each label. Links and selectable text use normal iOS
       interaction.
+- [ ] Open issue #50 and verify its body renders separate paragraphs and a
+      two-item unordered list. Add or edit a comment containing two paragraphs,
+      an unordered list, emphasis, and a link; verify every Markdown block and
+      inline style renders correctly after saving and after pull-to-refresh.
 - [ ] Tap the **Add comment** icon on an issue. Enter headings, emphasis, a
       list, link, and fenced code block; **Write** syntax-highlights the
       Markdown, **Preview** renders it, and switching modes preserves the exact
@@ -220,7 +224,9 @@ xcrun simctl launch booted de.rfc1437.gotcha
 - [ ] Open a commit and verify its header shows the full title and description,
       full hash, author, committer, date, known branch/ref, and signature status
       above the Changed Files paths and statuses. Unsigned commits say
-      **Unsigned**. Check that long values wrap and remain readable at the
+      **Unsigned**. Verify paragraphs, lists, links, and inline styles in a
+      multi-line commit description use the repository file Preview Markdown
+      presentation. Check that long values wrap and remain readable at the
       largest Dynamic Type accessibility size.
 - [ ] Open a changed file and verify the diff title, old/new line numbers,
       monospaced text, addition/removal/hunk colors, vertical scrolling, and
@@ -300,6 +306,9 @@ xcrun simctl launch booted de.rfc1437.gotcha
 - [ ] Each milestone shows its title, description, state, due date, issue
       counts, and a green/amber closed/open progress bar. Lists and details show
       a green open or purple closed icon and VoiceOver announces the state.
+- [ ] A milestone description containing multiple paragraphs, a list, emphasis,
+      and a link uses the repository file Preview Markdown presentation in both
+      the milestone list and detail.
 - [ ] Open a milestone and verify every assigned issue and pull request is
       listed; tapping either opens its normal detail.
 - [ ] Tap the add button. **New Milestone** has native Cancel and Save controls,