A GPS track (.gpx) in a repository renders as its route drawn as an outline, with distance and climb #10329

Done when:

• [x] A .gpx file on a repository's file page renders server-side as an inline SVG outline of its tracks and routes (equirectangular projection fitted to the bounds, no map tiles, no network), with total distance, elevation gain and point count beside it.
• [x] A small pure parser (src/web/render/gpx.ts), no dependency, no XML entity expansion; names escaped; a malformed file falls back to text; more than 20,000 points are thinned evenly, not dropped at the end.
• [x] Registered in src/web/render/kinds.ts and renderers.ts; tests in test/render-gpx.test.ts: distance of a known two-point track within 1%, a malformed file, an entity-expansion attempt that is not expanded.

Files: src/web/render/gpx.ts, kinds.ts, renderers.ts, test/render-gpx.test.ts.

Reviewed pull #10382 at its head: ticked A .gpx file on a repository's file page renders server-side as an inline SVG outline of its tracks and routes (equirectangular projection fitted to the bounds, no map tiles, no network), with total distance, elevation gain and point count beside it.; A small pure parser (src/web/render/gpx.ts), no dependency, no XML entity expansion; names escaped; a malformed file falls back to text; more than 20,000 points are thinned evenly, not dropped at the end.; Registered in src/web/render/kinds.ts and renderers.ts; tests in test/render-gpx.test.ts: distance of a known two-point track within 1%, a malformed file, an entity-expansion attempt that is not expanded..