Observed: both non-maintainer users (pistazie, nelli) created a route,
never planned in it, and stopped. The Route detail page rendered as a
dead end — name, a row of buttons, then blank.
Changes:
- Detect "empty" as no geometry AND no distance (the state every new
route has before any planning happens).
- When empty, hide the top-row button cluster (Edit in Planner / Edit
/ Export GPX) and render a centered dashed-border card in its place.
- Card shows: large headline, short body (owner-specific vs
viewer-only copy), primary "Open in Planner" button (same action as
the existing top-row button, just visually prominent), and a
secondary "or upload a GPX file" link to the edit page.
- Bilingual copy added under routes.empty.*.
No non-empty route loses any UI — those paths stay identical.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>