Make the config file the only home for settings

With no production instance yet, there is no reason to carry two ways
of configuring the agent. Every environment variable that duplicated a
config key is gone; the environment now supplies only the secrets the
file references by ${…}, plus NISSE_CONFIG and NISSE_ENV to find the
files.

- AgentConfig loads from a file (load, from_file) or a parsed tree
  (from_tree, for tests); a missing file is an error naming the example
- The from_env constructors on LiteLLMClient, AnthropicPassthroughClient,
  GiteaClient, MatrixConfig and RoleMap are removed, with the env
  reading for max output tokens; clients take their settings from config
- The live integration tests share a committed agent config,
  tests/integration/nisse-test.yaml, aimed at test resources, and one
  conftest that loads it and builds clients. NISSE_LIVE_PLANNER_MODEL
  becomes its planner role; NISSE_CAPABILITY_MODELS stays as a per-run
  switch
- A missing secret now fails the live tests instead of skipping them
- CI passes only the three tokens
- .env.example is secrets only; spec A5 says config comes from the file

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/integration/test_delegation_live.py

@@ -2,30 +2,18 @@
 working code and a structured handback out."""
 
 import io
-import os
 from pathlib import Path
 
 import pytest
 
 from nisse_dev.delegation import Caps, Delegation
-from nisse_dev.envfile import load_env_file
 from nisse_dev.git import GitRepo
 from nisse_dev.llm import AnthropicPassthroughClient
 from nisse_dev.oplog import OpLog
 from nisse_dev.state import StateStore
 from nisse_dev.tools import Workspace
 
-load_env_file(Path(__file__).resolve().parents[2] / ".env")
-
-SENTINEL = "NISSE_LIVE_PLANNER_MODEL"
-
-pytestmark = [
-    pytest.mark.integration,
-    pytest.mark.skipif(
-        not os.environ.get(SENTINEL),
-        reason=f"no live frontier route configured ({SENTINEL} unset)",
-    ),
-]
+pytestmark = pytest.mark.integration
 
 BRIEF = """Create `slugify.py` in the workspace root containing a function
 `slugify(text)` that lowercases the text and replaces every run of
@@ -34,7 +22,9 @@ hyphen. Then create `test_slugify.py` with at least two assertions covering
 it, and run `python -m pytest test_slugify.py -q` until it passes."""
 
 
-def build(tmp_path: Path, caps: Caps) -> tuple[Delegation, GitRepo, StateStore]:
+def build(
+    tmp_path: Path, caps: Caps, client: AnthropicPassthroughClient, model: str
+) -> tuple[Delegation, GitRepo, StateStore]:
     repo = GitRepo(tmp_path / "work")
     repo.init()
     repo.configure_identity("nisse-dev-testing", "n@t.test")
@@ -42,18 +32,22 @@ def build(tmp_path: Path, caps: Caps) -> tuple[Delegation, GitRepo, StateStore]:
     repo.commit_all("seed")
     store = StateStore(tmp_path / "state.db", oplog=OpLog("nisse-dev", io.StringIO()))
     delegation = Delegation(
-        AnthropicPassthroughClient.from_env(),
+        client,
         store,
         Workspace(repo.root, timeout_s=60),
         repo,
-        model=os.environ[SENTINEL],
+        model=model,
         caps=caps,
     )
     return delegation, repo, store
 
 
-def test_delegate_completes_a_scoped_subtask(tmp_path: Path) -> None:
-    delegation, repo, _store = build(tmp_path, Caps(turns=12, wall_clock_s=300.0))
+def test_delegate_completes_a_scoped_subtask(
+    tmp_path: Path, passthrough: AnthropicPassthroughClient, live_model: str
+) -> None:
+    delegation, repo, _store = build(
+        tmp_path, Caps(turns=12, wall_clock_s=300.0), passthrough, live_model
+    )
 
     result = delegation.run(brief=BRIEF, branch="live/delegation-1")
 
@@ -76,10 +70,14 @@ def test_delegate_completes_a_scoped_subtask(tmp_path: Path) -> None:
     assert check.success, f"delegate's own tests do not pass: {check.result[:400]}"
 
 
-def test_a_cap_breach_discards_the_work(tmp_path: Path) -> None:
+def test_a_cap_breach_discards_the_work(
+    tmp_path: Path, passthrough: AnthropicPassthroughClient, live_model: str
+) -> None:
     # One turn cannot finish the brief, so this exercises the abort path
     # against a real model rather than a scripted one.
-    delegation, repo, _ = build(tmp_path, Caps(turns=1, wall_clock_s=120.0))
+    delegation, repo, _ = build(
+        tmp_path, Caps(turns=1, wall_clock_s=120.0), passthrough, live_model
+    )
 
     result = delegation.run(brief=BRIEF, branch="live/delegation-2")