Add WebP quality control and selective visualization (--only / --skip)

- WebP output now uses quality=85 by default (down from lossless),
  reducing file size by ~75% (35MB → 5-8MB per visualization)
- Added --quality N (1-100) and --lossless flags in CLI and run.sh
- Added --only and --skip to select/exclude specific visualizations
  (e.g., --only hillshade,svf,lrm or --skip ortho,topo)
- VIZ_STEPS filtering is done in LidarArchaeoPipeline.__init__
- SharedDEM is skipped when all selected visualizations already exist
- Invalid visualization names are validated at startup with clear error

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

lidar_pipeline/rendering.py

@@ -271,7 +271,7 @@ def _nice_scale(extent_m):
     return chosen, f"{chosen} m"
 
 
-def tif_to_png(tif_file, vis_dir, resolution, keep_tif=False, source_info=None):
+def tif_to_png(tif_file, vis_dir, resolution, keep_tif=False, source_info=None, quality=85):
     """Convert GeoTIFF to visualization WebP with GPS coordinates, legend, and scale bar.
 
     Args:
@@ -279,6 +279,8 @@ def tif_to_png(tif_file, vis_dir, resolution, keep_tif=False, source_info=None):
         vis_dir: Output directory for the WebP file.
         resolution: Grid resolution in m/px.
         keep_tif: If True, keep the source TIFF after conversion.
+        source_info: Dict with method/date/basename for metadata.
+        quality: WebP quality (1-100). Use 100 for lossless. Default 85.
 
     Returns:
         Path to output WebP file, or None on failure.
@@ -589,7 +591,10 @@ def tif_to_png(tif_file, vis_dir, resolution, keep_tif=False, source_info=None):
                 plt.close()
 
             img = PILImage.open(str(png_temp))
-            img.save(str(webp_file), format='WEBP', lossless=True)
+            if quality >= 100:
+                img.save(str(webp_file), format='WEBP', lossless=True)
+            else:
+                img.save(str(webp_file), format='WEBP', quality=quality)
             png_temp.unlink(missing_ok=True)
 
             # Delete source TIFF (unless --keep-tif)