feat(tours): import KML and KMZ routes as tours, with a preview first

A route planned in Google My Maps or Google Earth can now become a tour
without converting it to GPX first. The import button and a file dropped on
the tours workspace take .kml and .kmz files beside .gpx, through the same
preview, the same import routes and the same transaction as a GPX file.

The preview shows every line of the file on its own, numbered, with its
distance and heights; two lines of one placemark are numbered after its name
and never joined. Heights count only where they are heights: kept for an
absolute line, dropped for any other altitude mode and for the all-zero
placeholder My Maps writes, so a missing height stays unknown. What the file
holds besides its lines (pins, areas, overlays, links to other files) is
counted in a dashed card, and nothing is fetched from elsewhere.

The KML reading reuses the place import's codec. A KMZ only ever has its KML
entry unpacked, counted byte by byte against the decompressed cap whatever
its header claims. A file that cannot be read is refused with its reason
(damaged, an archive without KML, too large unpacked), and the toast names
the file and the reason. A KML or KMZ import keeps the gpx origin of a file
import; its provenance names the real format from the stored file name.

client/src/api/tourGpx.ts

@@ -1,7 +1,7 @@
 import type { TourGpxImportFields, TourGpxPreviewResponse, TourImportGpxResponse } from '@trek/shared';
 import { postMultipart } from './client';
 
-/** A GPX file and the fields beside it, as the Tours import routes read a multipart body. */
+/** A GPX, KML or KMZ file and the fields beside it, as the Tours import routes read a multipart body. */
 function gpxForm(file: File, fields?: TourGpxImportFields): FormData {
   const fd = new FormData();
   fd.append('file', file);
@@ -9,7 +9,10 @@ function gpxForm(file: File, fields?: TourGpxImportFields): FormData {
   return fd;
 }
 
-/** The Tours GPX import: a file read for its preview first (PAD-02), then imported as the type chosen. */
+/**
+ * The Tours file import: a GPX, KML or KMZ file (IO-02) read for its preview
+ * first (PAD-02), then imported as the type chosen.
+ */
 export const tourGpxApi = {
   /** What the file holds, read by the import's own parser; nothing is stored. */
   preview: (tripId: number | string, file: File): Promise<TourGpxPreviewResponse> =>