feat: add pr list (task 0008)

Implements `pr list` with the two policies later PR slices reuse:
client-side filtering with the filtered-set count line (ADR 0005) and
the official-first reviewDecision via parallel per-PR review fetches
(ADR 0006), extracted into src/review.ts.

API-supported flags map to their params (--state, --author→poster,
--label name→ID, --label-id, --sort, --limit, --fields); --assignee,
--base, --head, and --draft filter in-process after full pagination,
with the count line's total taken from the filtered set. --search is
refused with a redirect to `search prs`.

Adds a boolText field extractor and a shared parsePositiveInt helper,
the latter also adopted by issue list's --limit parsing.

src/review.ts

@@ -0,0 +1,67 @@
+import type { PullReview } from "gitea-js";
+import type { GiteaClient } from "./client.js";
+import type { RepoContext } from "./context.js";
+import { classifyHttpError } from "./errors.js";
+
+/**
+ * gitea-axi's reviewDecision, the three-value result of {@link reviewDecision}.
+ * Deliberately narrower than gh-axi's four values: Gitea offers no non-admin way
+ * to tell whether review is formally required, so there is no `none` (ADR 0006).
+ */
+export type ReviewDecision = "approved" | "changes_requested" | "required";
+
+// Gitea's ReviewStateType is typed as a bare string; these are the two states
+// the decision turns on. A comment-only or pending review is neither, so it
+// falls through to `required`.
+const APPROVED = "APPROVED";
+const REQUEST_CHANGES = "REQUEST_CHANGES";
+
+/**
+ * Derive a PR's reviewDecision from its reviews, using the official-first
+ * fallback (ADR 0006): when any review is `official`, only official reviews
+ * count — preserving branch-protection semantics; otherwise every review counts,
+ * since unprotected repos never mark a review official and `approved` would
+ * otherwise be unreachable there.
+ *
+ * Within the considered set: a non-dismissed `REQUEST_CHANGES` wins as
+ * `changes_requested`; else a non-dismissed, non-stale `APPROVED` is `approved`;
+ * everything else — zero reviews, comment-only, stale or dismissed approvals —
+ * is `required`.
+ */
+export function reviewDecision(reviews: PullReview[]): ReviewDecision {
+  const hasOfficial = reviews.some((review) => review.official === true);
+  const considered = hasOfficial
+    ? reviews.filter((review) => review.official === true)
+    : reviews;
+
+  if (considered.some((review) => review.state === REQUEST_CHANGES && !review.dismissed)) {
+    return "changes_requested";
+  }
+  if (
+    considered.some(
+      (review) => review.state === APPROVED && !review.stale && !review.dismissed,
+    )
+  ) {
+    return "approved";
+  }
+  return "required";
+}
+
+/**
+ * Fetch a PR's reviews and reduce them to its reviewDecision. One HTTP call per
+ * PR — `pr list` issues these in parallel across the rows it renders (ADR 0006).
+ */
+export async function fetchReviewDecision(
+  api: GiteaClient,
+  context: RepoContext,
+  number: number,
+): Promise<ReviewDecision> {
+  let reviews: PullReview[];
+  try {
+    const response = await api.repos.repoListPullReviews(context.owner, context.name, number);
+    reviews = response.data ?? [];
+  } catch (error) {
+    throw classifyHttpError(error);
+  }
+  return reviewDecision(reviews);
+}