Fix hiking trails extraction: add-locations-to-ways was missing

Verified live on brick against real cached extracts: a plain Geofabrik
PBF's ways only carry bare node references, not coordinates, so
locations_on_ways on the final `cat -f opl` had nothing to embed —
every way came out as e.g. n123xy, empty x/y, and every relation got
dropped for having no usable geometry (0 routes for Macedonia).

osmium add-locations-to-ways between the tags-filter and cat steps
resolves those references first. Re-verified after the fix: 45 routes
for Macedonia, 3009 for Slovakia, with real colour/ref/operator/
distance (326 red, 782 yellow, 510 blue, 902 green KST-style routes).

lib/maptool/hiking_trails.rb

@@ -7,18 +7,26 @@ module Maptool
   # Prototype: extracts route=hiking relations (name/colour/network/operator,
   # full member-way geometry) straight out of a Geofabrik .osm.pbf — the same
   # file PmtilesBuilder already downloads per country for offline.pmtiles, so
-  # this needs no separate download or third-party service. Two osmium
+  # this needs no separate download or third-party service. Three osmium
   # subprocess steps do the heavy lifting (osmium is already a server
   # dependency, see PmtilesBuilder/docs/development.adoc):
   #
   #  1. `osmium tags-filter FILE r/route=hiking -o hiking.osm.pbf` — pulls
   #     out just the hiking relations *and* (by default, no -R) every way/
   #     node they reference, so the output is small and self-contained.
-  #  2. `osmium cat hiking.osm.pbf -f opl,locations_on_ways=true,add_metadata=false`
+  #  2. `osmium add-locations-to-ways` — a plain Geofabrik PBF's ways only
+  #     carry bare node *references* (ids), not coordinates; this resolves
+  #     each way's node ids against the node objects in the same file and
+  #     rewrites the way with real coordinates attached. Verified against a
+  #     real extract (Macedonia) that skipping this step silently produces
+  #     ways with empty x/y (`n123xy`, no numbers) in the OPL output below —
+  #     not an error, just wrong output, so easy to miss without checking.
+  #  3. `osmium cat hiking.osm.pbf -f opl,locations_on_ways=true,add_metadata=false`
   #     — OPL is a plain-text, one-object-per-line format (see
-  #     https://osmcode.org/opl-file-format/); locations_on_ways embeds each
-  #     way's node coordinates directly in its own line, so no separate
-  #     node-id -> [lon,lat] table needs building, just two passes over text.
+  #     https://osmcode.org/opl-file-format/); locations_on_ways (now that
+  #     step 2 actually populated them) embeds each way's node coordinates
+  #     directly in its own line, so no separate node-id -> [lon,lat] table
+  #     needs building, just two passes over text.
   #
   # No general OSM tool stitches a route relation's member ways into one
   # line for you (routes are a semantic grouping, not a geometry type) —
@@ -45,8 +53,11 @@ module Maptool
         filtered = File.join(dir, "hiking.osm.pbf")
         run!(osmium_bin, "tags-filter", pbf_path, "r/route=hiking", "-o", filtered)
 
+        located = File.join(dir, "hiking-located.osm.pbf")
+        run!(osmium_bin, "add-locations-to-ways", filtered, "-o", located)
+
         opl_path = File.join(dir, "hiking.opl")
-        run!(osmium_bin, "cat", filtered, "-f", "opl,locations_on_ways=true,add_metadata=false", "-o", opl_path)
+        run!(osmium_bin, "cat", located, "-f", "opl,locations_on_ways=true,add_metadata=false", "-o", opl_path)
 
         parse_opl(File.read(opl_path))
       end