rename privacy "private" → "unlisted"; enable GPS for unlisted

- "unlisted" = not shown in the public feed, but GPS track, timeseries
  and detail JSON are all accessible by direct URL (security by obscurity)
- "private" accepted as legacy alias everywhere (backward compat with
  existing data on disk)
- New writes from Strava sync / ZIP upload / sidecar use "unlisted"
- Only "no_gps" now suppresses the GPS track
- isUnlisted() helper in format.ts used by all Svelte/Astro components
- SCHEMA.md and CLAUDE.md document the privacy model and the distinction
  between "unlisted" and "no_gps"

site/public/data

@@ -0,0 +1 @@
+/private/tmp/bincio_dev_test