feat(2-7): operational radar loop, startup screen, and systemd wiring

Implements story 2-7: full main.py with _make_startup_screen(),
_run_one_cycle() with per-phase timing and slow-render warning, and
main() connecting config → bounds → fetcher → renderer → display.
Adds provision.py early-exit when already provisioned. Adds User=root
to both systemd service files. Adds tests/test_main.py (3 new tests,
99 total). Updates scaffold test to allow provisioning.config import
from main.py. All quality gates pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_main.py

@@ -0,0 +1,56 @@
+from __future__ import annotations
+
+import logging
+import pathlib
+from unittest.mock import MagicMock, patch
+
+import pytest
+from PIL import Image
+
+from planemapper.display import NullDisplay
+from planemapper.fetcher import FileFixtureFetcher
+from planemapper.main import _run_one_cycle
+from planemapper.renderer.projection import MapBounds
+from planemapper.renderer.renderer import Renderer
+
+FIXTURE_DIR = pathlib.Path(__file__).parent / "fixtures"
+
+
+@pytest.fixture
+def renderer(monkeypatch: pytest.MonkeyPatch) -> Renderer:
+    monkeypatch.setattr(
+        "planemapper.renderer.airspace.AIRSPACE_PATH",
+        FIXTURE_DIR / "airspace_sample.geojson",
+    )
+    base_map = Image.new("RGB", (800, 480), color=(255, 255, 255))
+    bounds = MapBounds(home_lat=53.0, home_lon=-6.0, radius_nm=100.0)
+    return Renderer(base_map, bounds)
+
+
+def test_run_one_cycle_calls_display_show(renderer: Renderer) -> None:
+    fetcher = FileFixtureFetcher(FIXTURE_DIR / "aircraft_sample.json")
+    display = NullDisplay()
+    display_mock = MagicMock(wraps=display)
+    _run_one_cycle(renderer, fetcher, display_mock)
+    display_mock.show.assert_called_once()
+
+
+def test_run_one_cycle_logs_warning_when_slow(
+    renderer: Renderer, caplog: pytest.LogCaptureFixture
+) -> None:
+    fetcher = FileFixtureFetcher(FIXTURE_DIR / "aircraft_sample.json")
+    display = NullDisplay()
+    # Simulate 43s total: t0=0, t1=1, t2=2, t3=43
+    with patch("planemapper.main.time.monotonic", side_effect=[0.0, 1.0, 2.0, 43.0]):
+        with caplog.at_level(logging.WARNING, logger="planemapper.main"):
+            _run_one_cycle(renderer, fetcher, display)
+    assert any("render slow" in r.message for r in caplog.records)
+
+
+def test_provision_main_exits_if_already_provisioned() -> None:
+    with patch("planemapper.provisioning.config.read", return_value={"provisioned": True}):
+        with patch("planemapper.provisioning.wifi.start_ap") as mock_ap:
+            from planemapper.provision import main as provision_main
+
+            provision_main()
+            mock_ap.assert_not_called()