Fix E2E select locator, remove maxspeed mode (data unavailable)

E2E fixes:
- Color mode select locator uses option[value='highway'] filter
  instead of fragile page.locator("select").last()

Removed maxspeed color mode:
- BRouter does not expose maxspeed in WayTags output despite the tag
  existing in its lookup table. The dummyUsage profile trick only
  affects cost calculation, not tiledesc output.
- Can revisit if BRouter adds maxspeed to WayTags in a future version
  or if we fork/patch the BRouter profiles more deeply.

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

e2e/fixtures/brouter-mock.ts

@@ -40,10 +40,6 @@ const MOCK_ROUTE_3WP = {
     "residential", "residential", "cycleway", "cycleway", "path",
     "path", "tertiary", "tertiary", "residential", "residential",
   ],
-  maxspeeds: [
-    "30", "30", "unknown", "unknown", "unknown",
-    "unknown", "50", "50", "30", "30",
-  ],
 };
 
 /**
@@ -80,9 +76,6 @@ const MOCK_ROUTE_2WP = {
   highways: [
     "secondary", "secondary", "cycleway", "cycleway", "residential", "residential",
   ],
-  maxspeeds: [
-    "50", "50", "unknown", "unknown", "30", "30",
-  ],
 };
 
 /**