Add web map with zone generation API, side job queue, and restore historical DTM hole rendering

- webapp.py: FastAPI serving the continuous map (port 8973) with
  /api/preview, /api/generate and /api/status; tiles are downloaded
  from IGN and processed in a logged subprocess, tracked live in a
  side "File de génération" panel that survives page reloads
- fetch_ign.py: download missing 1 km LiDAR HD tiles from the IGN
  geoplateforme before processing
- index.py: tile thumbnails and 500 m subtiles are now invalidated by
  mtime so regenerating a tile refreshes its cached images; progress
  logging per tile
- dtm.py: back to the historical gap handling (small gaps filled by
  fillnodata only, larger holes left as nodata rendered black);
  lowest-return floor only via --bare-earth, IGN class selection via
  --ign-classes
- cli.py: positional input now optional (--rebuild-index works alone)
- docker-compose.yml: serve (GPU, port 8973) and process services;
  launch via docker compose only (documented in AGENTS.md/AGENTS.md)
- tests: 131 passing, incl. regressions for thumbnail staleness,
  --rebuild-index without input, and nodata rendering

lidar_pipeline/tests/test_fetch_ign.py

@@ -0,0 +1,98 @@
+"""Tests du téléchargement des dalles LiDAR HD de l'IGN (fetch_ign)."""
+
+
+def test_parse_tile_specs():
+    """Accepte 'col,row', 'col:row' et ignore les espaces."""
+    from lidar_pipeline.fetch_ign import parse_tile_specs
+    assert parse_tile_specs(["1055,6882"]) == [(1055, 6882)]
+    assert parse_tile_specs(["1055:6883", " 651 , 6630 "]) == [(1055, 6883), (651, 6630)]
+
+
+def test_parse_tile_specs_rejects_invalid():
+    """Les spécifications mal formées lèvent une erreur explicite."""
+    import pytest
+    from lidar_pipeline.fetch_ign import parse_tile_specs
+    with pytest.raises(ValueError):
+        parse_tile_specs(["1055"])
+    with pytest.raises(ValueError):
+        parse_tile_specs(["abc,def"])
+    with pytest.raises(ValueError):
+        parse_tile_specs(["1055,6882,9999"])
+
+
+def test_tile_filename_pads_coordinates():
+    """Le nom de fichier DALLE utilise des coordonnées à 4 chiffres."""
+    from lidar_pipeline.fetch_ign import tile_filename
+    assert tile_filename(1055, 6882) == "LHD_FXX_1055_6882_PTS_LAMB93_IGN69.copc.laz"
+    assert tile_filename(651, 6630) == "LHD_FXX_0651_6630_PTS_LAMB93_IGN69.copc.laz"
+
+
+def test_match_feature_uses_coordonnees_nw():
+    """La correspondance se fait sur lidarhd:coordonnees_NW (format 0816-6847)."""
+    from lidar_pipeline.fetch_ign import match_feature
+    features = [
+        {"id": "LHD_FXX_1054_6882_PTS_LAMB93_IGN69_NE",
+         "properties": {"lidarhd:coordonnees_NW": "1054-6882"},
+         "assets": {"data": {"href": "https://example.org/a.copc.laz"}}},
+        {"id": "LHD_FXX_1055_6882_PTS_LAMB93_IGN69_NE",
+         "properties": {"lidarhd:coordonnees_NW": "1055-6882"},
+         "assets": {"data": {"href": "https://example.org/b.copc.laz"}}},
+    ]
+    assert match_feature(features, 1055, 6882) is features[1]
+    assert match_feature(features, 9999, 9999) is None
+
+
+def test_find_tile_url_matches_and_returns_href(monkeypatch):
+    """find_tile_url interroge le STAC et retourne l'href de l'asset data."""
+    from lidar_pipeline import fetch_ign
+
+    class FakeResponse:
+        def __init__(self, payload):
+            self._payload = payload.encode("utf-8")
+
+        def read(self):
+            return self._payload
+
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *args):
+            return False
+
+    payload = ('{"features": [{"properties": {"lidarhd:coordonnees_NW": "1055-6882"},'
+               '"assets": {"data": {"href": "https://data.geopf.fr/x.copc.laz"}}}]}')
+    captured = {}
+
+    def fake_urlopen(req, timeout=None):
+        captured["url"] = req.full_url
+        return FakeResponse(payload)
+
+    monkeypatch.setattr(fetch_ign.urllib.request, "urlopen", fake_urlopen)
+    url = fetch_ign.find_tile_url(1055, 6882)
+    assert url == "https://data.geopf.fr/x.copc.laz"
+    assert "api.stac.teledetection.fr" in captured["url"]
+    assert "bbox=" in captured["url"]
+
+
+def test_fetch_tiles_skips_existing_and_generated(tmp_path, monkeypatch):
+    """Pas de téléchargement si le LAZ existe ou si les visualisations existent."""
+    from lidar_pipeline import fetch_ign
+
+    input_dir = tmp_path / "input"
+    input_dir.mkdir()
+    output_dir = tmp_path / "output"
+    vis_dir = output_dir / "visualisations" / "LHD_FXX_1054_6882_PTS_LAMB93_IGN69"
+    vis_dir.mkdir(parents=True)
+
+    # 1054,6882 : visualisations déjà générées
+    # 1055,6882 : LAZ déjà présent
+    existing = input_dir / fetch_ign.tile_filename(1055, 6882)
+    existing.write_bytes(b"naze")
+
+    def fail_download(*args, **kwargs):
+        raise AssertionError("ne doit pas être appelé")
+
+    monkeypatch.setattr(fetch_ign, "find_tile_url", fail_download)
+    result = fetch_ign.fetch_tiles(input_dir, [(1054, 6882), (1055, 6882)],
+                                   output_dir=output_dir)
+    assert result == []