wip: pull request view & md rendering

fixtures/github/issues.pull_request_timeline.PR_kwDONovem84.page1.json

@@ -0,0 +1,68 @@
+{
+  "node": {
+    "__typename": "PullRequest",
+    "timelineItems": {
+      "pageInfo": {
+        "endCursor": "timeline:PR_kwDONovem84:page1",
+        "hasNextPage": false
+      },
+      "nodes": [
+        {
+          "__typename": "AssignedEvent",
+          "createdAt": "2026-05-01T09:20:00Z",
+          "actor": {
+            "__typename": "User",
+            "login": "kennethnym",
+            "avatarUrl": "https://avatars.githubusercontent.com/u/4242?v=4"
+          },
+          "assignee": {
+            "__typename": "Bot",
+            "login": "triage-bot",
+            "avatarUrl": "https://avatars.githubusercontent.com/in/98765?v=4"
+          }
+        },
+        {
+          "__typename": "PullRequestCommit",
+          "commit": {
+            "committedDate": "2026-05-01T10:05:00Z",
+            "abbreviatedOid": "2bc41de",
+            "messageHeadline": "Hydrate issue pane from cached dashboard state"
+          }
+        },
+        {
+          "__typename": "CrossReferencedEvent",
+          "createdAt": "2026-05-01T12:00:00Z",
+          "actor": {
+            "__typename": "User",
+            "login": "kennethnym",
+            "avatarUrl": "https://avatars.githubusercontent.com/u/4242?v=4"
+          }
+        },
+        {
+          "__typename": "ReviewRequestedEvent",
+          "createdAt": "2026-05-01T12:05:00Z",
+          "actor": {
+            "__typename": "User",
+            "login": "kennethnym",
+            "avatarUrl": "https://avatars.githubusercontent.com/u/4242?v=4"
+          },
+          "requestedReviewer": {
+            "__typename": "Bot",
+            "login": "novem-ci",
+            "avatarUrl": "https://avatars.githubusercontent.com/in/54321?v=4"
+          }
+        },
+        {
+          "__typename": "IssueComment",
+          "createdAt": "2026-05-01T12:20:00Z",
+          "author": {
+            "__typename": "User",
+            "login": "kennethnym",
+            "avatarUrl": "https://avatars.githubusercontent.com/u/4242?v=4"
+          },
+          "body": "Cache hydration is now stable across refetches."
+        }
+      ]
+    }
+  }
+}