A repository per test run instead of the shared sandbox

Every live test that touches a repository gets one of its own from
e2e_support.fresh_repo, made by the test operator as an operator makes a
project's (D4, D8): seeded from tests/integration/seed/ (the sandbox's
package, without past runs' leftovers), the agent's account a collaborator
with write access, main protected (pushes only by the owner, an approval to
merge), and a deploy key generated for the run. It is deleted afterwards
(NISSE_E2E_KEEP_REPOS keeps it); scripts/e2e-cleanup.sh deletes leftovers.

- Both e2e fixtures use it; per-run base branches are gone. The merge
  helper approves first, as the protection now requires.
- test_gitea_live uses it, so CI needs NISSE_OPERATOR_TOKEN and no longer
  writes the sandbox deploy key (NISSE_PUSH_KEY).
- A live test of the helper: seeded, shared with the agent, protected
  against it, deleted.
- nisse-test.yaml's project entry is a placeholder; pytest and ruff skip
  the seed.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

tests/integration/test_fresh_repo_live.py

@@ -0,0 +1,33 @@
+"""The per-run test repository (e2e_support.fresh_repo): what the operator
+provides for a project (D4, D8), made and deleted by the test operator."""
+
+import uuid
+from pathlib import Path
+
+import pytest
+from e2e_support import fresh_repo, operator_gitea
+
+from nisse_dev.config import AgentConfig
+from nisse_dev.gitea import GiteaClient, GiteaError
+
+pytestmark = pytest.mark.integration
+
+
+def test_a_fresh_repository_is_seeded_shared_and_protected(
+    tmp_path: Path, live_config: AgentConfig, gitea: GiteaClient
+) -> None:
+    operator = operator_gitea(live_config.gitea_url)
+    run = uuid.uuid4().hex[:8]
+    with fresh_repo(operator, run, tmp_path / "keys", agent=gitea.whoami()) as repo:
+        # Seeded: the package and its tests, and the README replaced.
+        text = gitea._request("GET", f"/repos/{repo.name}/contents/sandbox/text.py")
+        assert text["name"] == "text.py"
+        assert gitea._request("GET", f"/repos/{repo.name}/contents/tests")
+        # The agent sees it as a collaborator that may push, and main as
+        # protected against it (what D4's verification reads).
+        main = gitea._request("GET", f"/repos/{repo.name}/branches/main")
+        assert main["protected"] and not main["user_can_push"]
+        assert gitea._request("GET", f"/repos/{repo.name}")["permissions"]["push"]
+        assert repo.push_key.exists()
+    with pytest.raises(GiteaError, match="404"):
+        gitea._request("GET", f"/repos/{repo.name}")