Fix bugs and improve pipeline flexibility

- Fix gpu_cleanup import missing in visualizations.py (NameError in workers)
- Fix t_pdf referenced before assignment when PDF is skipped
- Skip classification+DTM when DTM exists regardless of --force
- --force now only regenerates WebP/PDF, not classification/DTM
- --force-classification forces reclassification when needed
- Add laspy repair fallback for corrupt LAZ files (EVLR errors)
- Keep DTM TIF by default for reuse (--no-keep-tif to delete)
- Increase space between image and bottom cartouche (0.12→0.19)

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

lidar_pipeline/pipeline.py

@@ -275,9 +275,11 @@ class LidarArchaeoPipeline:
         logger.info(f"FICHIER : {basename}")
         logger.info("=" * 60)
 
-        # Skip ground classification + DTM if DTM already exists (unless --force)
+        # Skip ground classification + DTM if DTM already exists
+        # --force only affects visualizations/PDF, not classification/DTM
+        # Use --force-classification to force reclassification
         dtm_path = self.dtm_dir / f"{basename}_dtm.tif"
-        if dtm_path.exists() and not self.force:
+        if dtm_path.exists():
             logger.info("[1/5] Classification du sol — sautée (DTM existant)")
             logger.info("[2/5] Génération DTM — sautée (DTM existant)")
             dtm_file = dtm_path
@@ -297,7 +299,7 @@ class LidarArchaeoPipeline:
             # Step 2: Generate DTM
             logger.info("[2/5] Génération DTM...")
             t2 = time.time()
-            dtm_file = create_dtm_fast(las_file, basename, self.dtm_dir, self.resolution, force=self.force)
+            dtm_file = create_dtm_fast(las_file, basename, self.dtm_dir, self.resolution)
             t_dtm = time.time() - t2
             if not dtm_file:
                 logger.error(f"  ✗ Échec DTM ({t_dtm:.1f}s)")
@@ -309,6 +311,7 @@ class LidarArchaeoPipeline:
         self.generate_all_visualizations(dtm_file, basename)
 
         # Step 4: PDF report
+        t_pdf = 0
         file_vis_dir = self.vis_dir / basename
         pdf_file = self.pdf_dir / f"{basename}_rapport.pdf"
         if pdf_file.exists() and not self.force:
@@ -320,10 +323,8 @@ class LidarArchaeoPipeline:
             t_pdf = time.time() - t4
             logger.info(f"  ✓ Rapport PDF terminé ({t_pdf:.1f}s)")
 
-        # Step 5: Clean up DTM TIF unless --keep-tif
-        if not self.keep_tif:
-            for dtm_file in sorted(self.dtm_dir.glob(f"{basename}_dtm.tif")):
-                dtm_file.unlink(missing_ok=True)
+        # Step 5: Keep DTM TIF for reuse (regenerating WebPs skips classification)
+        # Use --no-keep-tif to delete DTM files after processing
 
         t_total = time.time() - t_start
         logger.info(f"✓ {basename} terminé en {t_total:.1f}s")