Add multi-resolution support and remove PDF generation

- --resolution now accepts comma-separated values (e.g. 0.5,0.2)
- Additional resolutions get suffixed output dirs: basename_r0p2/
- DTM files are named basename_dtm_r0p2.tif for extra resolutions
- Ground classification is done once and shared across resolutions
- PDF report generation removed per user request
- Fix --file argument to accept full filenames with extensions

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

lidar_pipeline/cli.py

@@ -97,9 +97,9 @@ Exemples:
     )
     parser.add_argument(
         "-r", "--resolution",
-        type=float,
-        default=0.5,
-        help="Résolution en mètres par pixel (défaut: 0.5)"
+        type=str,
+        default="0.5",
+        help="Résolution en m/px, ou multiples séparées par virgules (défaut: 0.5, ex: 0.5,0.2)"
     )
     parser.add_argument(
         "-w", "--workers",