Re-add speed limit color mode with BRouter profile patch

The dummyUsage trick needs a separate assign per tag:
  assign dummyUsage2 = maxspeed=
(not appended to the existing smoothness= line)

- Dockerfile: Patch all BRouter profiles to include maxspeed in
  WayTags output via separate assign dummyUsage2
- brouter.ts: Extract maxspeed with direction handling
  (maxspeed:forward/backward + reversedirection awareness)
- ColoredRoute: maxspeed color mode (green ≤30, yellow ≤50,
  orange ≤70, red ≤100, dark red 100+)
- ElevationChart: maxspeed chart rendering, legend, hover "X km/h"
- PlannerMap: maxspeeds state + Yjs read + prop passing
- i18n: EN "Speed Limit" / DE "Tempolimit"
- Mock fixtures: maxspeed data for E2E tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker/brouter/Dockerfile

@@ -20,6 +20,16 @@ RUN addgroup --system app && adduser --system --ingroup app app \
 RUN cp -r profiles2/* /data/profiles/ 2>/dev/null || true \
     && mv brouter-*-all.jar brouter.jar
 
+# Patch profiles to include maxspeed in WayTags output (for speed limit visualization)
+# Each tag needs its own assign statement to appear in tiledesc WayTags
+RUN for f in /data/profiles/*.brf; do \
+      if grep -q "dummyUsage" "$f" && ! grep -q "maxspeed" "$f"; then \
+        sed -i '/assign dummyUsage/a assign dummyUsage2 = maxspeed=' "$f"; \
+      elif ! grep -q "maxspeed" "$f" && grep -q "context:node" "$f"; then \
+        sed -i '/---context:node/i assign dummyUsage2 = maxspeed=' "$f"; \
+      fi; \
+    done
+
 USER app
 EXPOSE 17777