style(map): thin out road shields at high/navigation zoom

414198b widened ref-shield symbol-spacing but the stops clamped at z14-15, so at navigation zoom (z16+, pitched) the long visible road still showed many A57/B/L/K shields. Extend the autobahn/bundes-/land-/kreisstrasse symbol-spacing stops to z16-18 with larger values (e.g. autobahn 750@z15 -> 1500@z16 -> 2500@z18) so shields thin out when zoomed in. Lower-zoom values unchanged.

Author: Medformatik

apps/web/public/styles/openmapx-streets.json

@@ -2708,7 +2708,7 @@
         },
         "symbol-spacing": {
           "base": 1,
-          "stops": [[7, 2500], [9, 2000], [11, 1250], [13, 1000], [15, 750]]
+          "stops": [[7, 2500], [9, 2000], [11, 1250], [13, 1000], [15, 750], [16, 1500], [18, 2500]]
         },
         "text-field": "{ref}",
         "text-font": ["Noto Sans Bold"],
@@ -2747,7 +2747,7 @@
         },
         "symbol-spacing": {
           "base": 1,
-          "stops": [[8, 2500], [10, 1750], [12, 1250], [14, 900]]
+          "stops": [[8, 2500], [10, 1750], [12, 1250], [14, 900], [16, 1500], [18, 2400]]
         }
       },
       "paint": {
@@ -2781,7 +2781,7 @@
         },
         "symbol-spacing": {
           "base": 1,
-          "stops": [[10, 2500], [12, 1500], [14, 1000]]
+          "stops": [[10, 2500], [12, 1500], [14, 1000], [16, 1500], [18, 2400]]
         }
       },
       "paint": {
@@ -2812,7 +2812,7 @@
         "symbol-placement": "line",
         "symbol-spacing": {
           "base": 1,
-          "stops": [[12, 2000], [14, 1250]]
+          "stops": [[12, 2000], [14, 1250], [16, 1600], [18, 2400]]
         }
       },
       "paint": {