feat: add pr view and checks (task 0009)

Add `pr view <n>` and `pr checks <n>`, built on the truncation machinery
and review fetches from earlier slices.

`pr view` uses the three-call fetch pattern (PR + reviews in parallel, then
the head commit's combined status) so `checks`, `comment_count`, and
`review_count` are in the default output; `--comments`, `--reviews`, and
`--full` behave as on `issue view`, with `--reviews` exposing Gitea's
`official`/`stale` fields plus per-review inline comments.

`pr checks <n>` renders the checks summary line and the `{ name, conclusion }`
rows, or the scalar no-CI message when no statuses exist.

The state→conclusion mapping and summary live in a new `src/checks.ts`;
`commentRows` is extracted into `src/comment.ts` and shared with `issue view`.

src/comment.ts

@@ -38,3 +38,30 @@ export function commentItem(
     body: options.full ? body : truncateBody(body, COMMENT_TRUNCATE_LIMIT, options.host),
   };
 }
+
+export interface CommentRowsOptions {
+  host: string;
+  /** Echo bodies untruncated, as `--full` asks. */
+  full: boolean;
+  now: Date;
+}
+
+/**
+ * The `{ author, created, body }` rows for a `--comments` block, shared by
+ * `issue view` and `pr view`. Each body is cleaned and truncated at 800 chars
+ * unless `full` is set. Ordered author→created→body, matching the block header
+ * both commands render.
+ */
+export function commentRows(
+  comments: Comment[],
+  options: CommentRowsOptions,
+): Record<string, unknown>[] {
+  return comments.map((comment) => {
+    const body = comment.body ?? "";
+    return {
+      author: comment.user?.login ?? "",
+      created: relativeTime(comment.created_at, options.now),
+      body: options.full ? body : truncateBody(body, COMMENT_TRUNCATE_LIMIT, options.host),
+    };
+  });
+}