Upgrade colormaps to Crameri scientific palette and fix IGN location map

- Replace RdBu_r with Crameri roma for all 6 relief-family colormaps
  (curvature, mslrm, lrm, tpi, sailore, aniso_open): perceptually
  uniform, CVD-friendly, dark center makes near-zero values visible
- Replace hsv with twilight for aspect: perceptually uniform cyclic
  colormap with no hue discontinuity
- Add cmcrameri dependency (falls back to RdBu_r if unavailable)
- Fix IGN location map: pass min_zoom=8 to download_ign_tiles so zoom
  10 context maps work (was hardcoded to min_zoom=15, blocking the
  loop entirely for zoom_level=10)
- Expand location map context from 3x extent to 80km fixed radius for
  better regional context at zoom 10
- Remove dead code: flow colormap entry, _nice_scale dead loop,
  aspect='auto' in location map imshow, outdated PDF report order list
- Fix SVF docstring: 8 directions → 16 directions

Dockerfile

@@ -42,7 +42,8 @@ RUN pip3 install --no-cache-dir \
     fastapi \
     uvicorn \
     piexif \
-    pillow-avif-plugin
+    pillow-avif-plugin \
+    cmcrameri
 
 # Install CuPy for GPU acceleration (optional - will fallback to numpy if not available)
 RUN pip3 install --no-cache-dir cupy-cuda12x || echo "CuPy not available - GPU acceleration disabled"