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

docs/Development-Plan.md

@@ -54,8 +54,14 @@ Only `nisse-dev` has real code; `nisse-core` and `nisse-ops` are placeholders.
 - **Models by role today:** executor `qwen3.8-27b`, planner and helper
   `claude-opus-5-5`, expert `claude-haiku-4-5`. Phase 2 moves to driver and helpers.
 - **Bring-up** runs on this development VM (`scripts/bringup.sh`), against test
-  resources: the sandbox repository, the test Matrix room, a budget-capped LiteLLM
-  key; configuration in `/root/nisse-e2e/`.
+  resources: a test repository, the test Matrix room, a budget-capped LiteLLM key;
+  configuration in `/root/nisse-e2e/`.
+- **Test repositories are made per run** by the test operator
+  (`nisse-testing-operator`, `NISSE_OPERATOR_TOKEN`), as an operator provides a
+  project's: seeded from `tests/integration/seed/`, the agent a collaborator,
+  `main` protected, a deploy key of its own; deleted afterwards
+  (`scripts/e2e-cleanup.sh` for leftovers). They replaced the shared sandbox
+  repository, whose state accumulated across runs.
 - **A build VM for bring-up** is provided by the operator by hand until Terraform
   (Phase 6); the agent reaches it over SSH with a key from `/root/nisse-e2e/ssh/`.
 
@@ -68,7 +74,7 @@ Only `nisse-dev` has real code; `nisse-core` and `nisse-ops` are placeholders.
   discussion first.
 - **Every change comes with tests,** through `scripts/check.sh`.
 - **The end-to-end test follows each milestone** (M1.6): the real agent, real models,
-  the Gitea sandbox and a real build host, driven by a scripted operator. It runs
+  a repository of the run's own and a real build host, driven by a scripted operator. It runs
   after each milestone, not on every push, since it spends model tokens. Manual
   live runs are for the new loop's first runs and phase ends. Findings are filed as
   issues and either fixed before moving on or deliberately deferred.