nisse-review: one unlistable repository holds up no other

Found at bring-up: an empty private repository's /pulls answered 404, and
intake stopped there, so the whole round failed and nothing was reviewed.
A repository whose PRs can't be listed is now logged (intake.repo_failed)
and skipped for the round; its items stay as they are.

Also, from nisse-review's review of this PR: a two-page test pins the
search listing the patterns rest on.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J5Utyfzw7gF7UhjRDEtjTk

nisse-core/tests/test_gitea.py

@@ -375,6 +375,23 @@ def test_visible_repositories_read_the_search_and_a_404_is_not_found() -> None:
         gitea.repository("d/gone")
 
 
+def test_visible_repositories_page_through_the_search() -> None:
+    # The patterns rest on the search listing everything (#154's review).
+    asked: list[dict[str, str]] = []
+
+    def handler(request: httpx.Request) -> httpx.Response:
+        asked.append(dict(request.url.params))
+        page = int(request.url.params["page"])
+        count = PR_PAGE_SIZE if page == 1 else 3
+        data = [{"full_name": f"o/r{page}-{n}"} for n in range(count)]
+        return httpx.Response(200, json={"ok": True, "data": data})
+
+    found = client(handler).visible_repositories()
+    assert len(found) == PR_PAGE_SIZE + 3 and found[-1] == "o/r2-2"
+    assert [a["page"] for a in asked] == ["1", "2"]
+    assert all(a["limit"] == str(PR_PAGE_SIZE) for a in asked)
+
+
 def test_a_pull_request_carries_what_a_review_needs() -> None:
     def handler(request: httpx.Request) -> httpx.Response:
         if request.url.path.endswith(".diff"):