Fix Edit/Delete on notes saved before properties.id existed

The earliest notes (saved before the previous commit added id
tracking) have no properties.id — update/delete target a feature by
that id, so offering Edit/Delete for one without it just 404s
("Could not delete/save the note", the generic fetch-failure alert).

The popup no longer offers Edit/Delete without an id. New
rake gpx:backfill_note_ids assigns one to any pre-existing Note
feature missing it, so already-saved notes become editable again too
— run once against wherever data/gpx actually lives (e.g. inside the
deployed container).

Rakefile

@@ -23,3 +23,33 @@ namespace :overpass do
     puts "Wrote #{geojson["features"].size} POIs to #{args[:out]}"
   end
 end
+
+namespace :gpx do
+  desc "Backfill properties.id on Note-category features saved before edit/delete (and its id targeting) existed"
+  task :backfill_note_ids do
+    require "json"
+    require "securerandom"
+
+    data_dir = ENV.fetch("MAPTOOL_DATA_DIR") { File.join(__dir__, "data") }
+    count = 0
+    Dir.glob(File.join(data_dir, "gpx", "**", "*.geojson")).each do |file|
+      # ".gpx.geojson"/".fit.geojson" are GpxStore's own cache sidecars for
+      # an uploaded GPX/FIT (regenerated from the source on demand, see
+      # GpxStore#geojson) — never hand-drawn notes, not worth touching.
+      next if file.end_with?(".gpx.geojson", ".fit.geojson")
+
+      collection = JSON.parse(File.read(file))
+      changed = false
+      (collection["features"] || []).each do |feature|
+        properties = (feature["properties"] ||= {})
+        next unless properties["category"] == "Note" && !properties["id"]
+
+        properties["id"] = SecureRandom.uuid
+        changed = true
+        count += 1
+      end
+      File.write(file, JSON.generate(collection)) if changed
+    end
+    puts "Backfilled #{count} note id(s)"
+  end
+end