feat: basic pr diff rendering

fixtures/github/issues.pull_request.PR_kwDOAgent47.json

@@ -1,4 +1,5 @@
 {
+  "id": "PR_kwDOAgent47",
   "title": "feat(prompts): split context loading from execution workers",
   "state": "OPEN",
   "is_draft": true,

fixtures/github/issues.pull_request.PR_kwDODesign31.json

@@ -1,4 +1,5 @@
 {
+  "id": "PR_kwDODesign31",
   "title": "chore(tokens): tighten dashboard spacing scale",
   "state": "OPEN",
   "is_draft": false,

fixtures/github/issues.pull_request.PR_kwDOInfra19.json

@@ -1,4 +1,5 @@
 {
+  "id": "PR_kwDOInfra19",
   "title": "docs(deploy): document manual failover steps",
   "state": "CLOSED",
   "is_draft": false,

fixtures/github/issues.pull_request.PR_kwDONovem84.json

@@ -1,4 +1,5 @@
 {
+  "id": "PR_kwDONovem84",
   "title": "feat(dashboard): hydrate issue pane from cached query state",
   "state": "OPEN",
   "is_draft": false,

fixtures/github/issues.pull_request.PR_kwDONovem85.json

@@ -1,4 +1,5 @@
 {
+  "id": "PR_kwDONovem85",
   "title": "feat(repo): add cached repository query for titlebar picker",
   "state": "OPEN",
   "is_draft": false,

fixtures/github/issues.pull_request.PR_kwDOSprint62.json

@@ -1,4 +1,5 @@
 {
+  "id": "PR_kwDOSprint62",
   "title": "feat(calendar): ship release handoff checklist in weekly planner",
   "state": "MERGED",
   "is_draft": false,

fixtures/github/issues.pull_request_file_tree.PR_kwDONovem85.json

@@ -0,0 +1,19 @@
+{
+  "node": {
+    "__typename": "PullRequest",
+    "files": {
+      "edges": [
+        {
+          "cursor": "file:PR_kwDONovem85:1",
+          "node": {
+            "changeType": "MODIFIED",
+            "additions": 42,
+            "deletions": 7,
+            "path": "src/api/repo.rs",
+            "viewerViewedState": "UNVIEWED"
+          }
+        }
+      ]
+    }
+  }
+}