Add visualization picker to zone generation and unify tile colors

- Web map: multi-select picker in the generation bar (aspect, slope,
  positive openness, anisotropic openness, wavelet) passed to the API;
  the layer panel is restricted to the same shortlist (PANEL_VIZ) and
  a refresh button rebuilds the index when new layers appear on disk;
  jobs started outside the UI are now adopted into the visible queue
- Uniform colors across tiles: openness/anisotropic/sailore now store
  local z-scores, and all renderers use fixed ranges (0-3 sigma, SVF
  0-1 physical, slope 0-30 deg) instead of per-tile percentile stretches
- Ray-tracing falls back to CPU when VRAM is exhausted so openness and
  SVF no longer fail silently on shared GPUs
- build_index merges visualizations available at only one resolution
  into the displayed tile so in-progress layers stay visible
- 11 new tests (142 passing)

lidar_pipeline/tests/test_webapp.py

@@ -79,3 +79,97 @@ def test_build_command_ground_classification():
             assert cmd[i + 1] == method
             assert ("--force" in cmd) == regenerate
             assert ("--force-classification" in cmd) == regenerate
+
+
+def test_build_command_default_viz_aspect():
+    """Sans choix de visualisation, la commande génère uniquement aspect."""
+    from lidar_pipeline.webapp import _build_command
+    cmd = _build_command([(1054, 6882)])
+    i = cmd.index("--only")
+    assert cmd[i + 1] == "aspect"
+
+
+def test_build_command_custom_viz():
+    """Les visualisations demandées sont passées à --only dans l'ordre."""
+    from lidar_pipeline.webapp import _build_command
+    cmd = _build_command([(1054, 6882)], viz=["aspect", "wavelet", "aniso_open"])
+    i = cmd.index("--only")
+    assert cmd[i + 1:i + 4] == ["aspect", "wavelet", "aniso_open"]
+
+
+def test_viz_step_names_match_pipeline():
+    """Les noms acceptés par l'API sont exactement les étapes VIZ_STEPS du pipeline."""
+    from lidar_pipeline.webapp import _viz_step_names
+    from lidar_pipeline.pipeline import VIZ_STEPS
+    assert _viz_step_names() == [n for n, _ in VIZ_STEPS]
+
+
+def test_generate_rejects_unknown_viz():
+    """L'API refuse un nom de visualisation inconnu (HTTPException 400)."""
+    from fastapi import HTTPException
+    from lidar_pipeline.webapp import generate, GenerateRequest
+    req = GenerateRequest(tiles=[[1054, 6882]], viz=["wavelet", "inconnu"])
+    try:
+        generate(req)
+        assert False, "une HTTPException était attendue"
+    except HTTPException as e:
+        assert e.status_code == 400
+        assert "inconnu" in e.detail
+
+
+def test_generate_accepts_wavelet_and_aniso():
+    """L'API accepte wavelet + aniso_open et les transmet à --only."""
+    import subprocess
+    import lidar_pipeline.webapp as webapp
+    captured = {}
+
+    def fake_popen(cmd, **kwargs):
+        captured["cmd"] = cmd
+
+        class _P:
+            def wait(self):
+                return 0
+
+            def poll(self):
+                return 0
+        return _P()
+
+    webapp.subprocess.Popen = fake_popen
+    try:
+        req = webapp.GenerateRequest(tiles=[[1054, 6882]],
+                                     viz=["wavelet", "aniso_open"])
+        result = webapp.generate(req)
+        assert result["demarré"] is True
+        i = captured["cmd"].index("--only")
+        assert captured["cmd"][i + 1:i + 3] == ["wavelet", "aniso_open"]
+    finally:
+        webapp.subprocess.Popen = subprocess.Popen
+
+
+def test_available_layers_scans_disk(tmp_path, monkeypatch):
+    """/api/layers retourne les couches présentes (clé → label)."""
+    import lidar_pipeline.webapp as webapp
+    monkeypatch.setattr(webapp, "OUTPUT_DIR", tmp_path)
+    vis = tmp_path / "visualisations" / "LHD_FXX_1054_6882_PTS_LAMB93_IGN69"
+    vis.mkdir(parents=True)
+    (vis / "LHD_FXX_1054_6882_PTS_LAMB93_IGN69_wavelet.avif").write_bytes(b"x")
+    layers = webapp.available_layers()
+    assert layers.get("wavelet")
+    assert "aspect" not in layers
+
+
+def test_rebuild_index_background(tmp_path, monkeypatch):
+    """POST /api/rebuild lance build_index en arrière-plan puis termine."""
+    import time as _time
+    import lidar_pipeline.webapp as webapp
+    import lidar_pipeline.index as index_mod
+    calls = []
+    monkeypatch.setattr(index_mod, "build_index", lambda out: calls.append(out))
+    assert webapp.rebuild_index()["demarré"] is True
+    for _ in range(100):
+        if not webapp.rebuild_status()["running"]:
+            break
+        _time.sleep(0.05)
+    assert calls  # build_index a bien été appelé
+    assert webapp.rebuild_status()["running"] is False
+    assert webapp.rebuild_status()["done"] is not None