Remove RRIM and Multi-Hillshade RGB, fix DTM resolution reuse bug, add --init to docker run

- Remove generate_rrim, generate_multi_hillshade, _compute_openness_both
- Remove corresponding VIZ_STEPS entries, COLORMAPS, RGB_LEGENDS, and tests
- Fix DTM resolution mismatch: existing DTM at different resolution is now
  regenerated instead of silently reused
- Propagate actual DTM resolution to visualizations and rendering
- Add --init to docker run commands for proper signal handling on Ctrl+C
- Add .playwright-mcp/ to .gitignore

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

run.sh

@@ -134,7 +134,7 @@ if [[ " $* " == *" --test "* ]]; then
     echo "============================================"
     echo " Tests unitaires LiDAR Pipeline"
     echo "============================================"
-    docker run --rm $GPU_FLAG \
+    docker run --rm --init $GPU_FLAG \
         "$IMAGE_NAME" \
         python3 -m pytest -v --pyargs lidar_pipeline.tests
     exit $?
@@ -174,7 +174,7 @@ if [ -n "$FILE_ARGS" ]; then
     CMD_ARGS="$CMD_ARGS --file $FILE_ARGS"
 fi
 
-docker run --rm $GPU_FLAG \
+docker run --rm --init $GPU_FLAG \
     --user 1000:1000 \
     -v "${INPUT_DIR}:/data/input:ro" \
     -v "${OUTPUT_DIR}:/data/output" \