End-to-end tests on a local model, and in CI on every PR

- Every e2e role runs on qwen3.8-27b on the RTX 4090 (e2e_roles();
  NISSE_E2E_MODEL overrides, e.g. claude-haiku-4-5). The first full run
  passed 7 of 8 in 26 minutes for $0.0000; the eighth was a real finding,
  fixed with the new-project PR.
- scripts/e2e.sh reports a run's spend on the test key and the day's total
  against its budget: above $0 on the local model means a paid fallback.
- CI runs the suite as its own job on pull requests (not pushes to main),
  on a throwaway sshd (--local), cancelling a run a newer push supersedes,
  so the checks job still reports in minutes.
- The plan says so: e2e on every PR; locally only -k / --lf.

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

docs/Development-Plan.md

@@ -73,9 +73,11 @@ Only `nisse-dev` has real code; `nisse-core` and `nisse-ops` are placeholders.
   `CLAUDE.md`. A milestone marked **needs discussion** starts with a design
   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,
-  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
+- **The end-to-end test runs on every PR** (M1.6): the real agent, every role on a
+  local model (so it costs nothing per call), a repository of the run's own and a
+  real build host, driven by a scripted operator. CI runs it as its own job on pull
+  requests, cancelling a run a newer push supersedes. Locally only the tests being
+  written (`-k`) or diagnosed (`--lf`); `scripts/e2e.sh` reports what a run spent. 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.
 - **The Quint models move with the loop:** `orchestrator.qnt` while `control.py`