feat(hikes): route-builder, overview map + cards, SAC-coloured pipeline

Build pipeline (scripts/build-hikes.ts) parses per-hike GPX, encodes
images via sharp, reverse-geocodes the centroid against Swisstopo and
emits a typed manifest under src/lib/data/hikes.generated.ts (gitignored).
Track JSON + image binaries live outside /static; served in dev by a
small hike-images plugin in vite.config.ts, in prod by nginx (private/
images proxied through Node + X-Accel-Redirect for auth-gating).

/hikes overview: full-bleed Swisstopo hero map (HikesOverviewMap) sits
under the sticky nav, drawing one polyline per route coloured by SAC
tier (T1 yellow Wegweiser, T2/T3 white-red-white, T4-T6 white-blue-
white). Click navigates, hover thickens + tooltips. Layer toggle,
recenter, GPS controls mirror the detail map (minus images toggle).
Cards drop the trail SVG, gain a per-route icon + SAC marker
pictogram on the cover, altitude range, season label, and "Neu" badge
for recently-published hikes. Filter bar + totals strip recompute over
the currently-visible set.

/hikes/[slug]: hero map with elevation profile, photo strip with map
sync, scroll-position pin, GPX download, SAC marker stats + min/max
altitude + season.

Route-builder (/hikes/route-builder): client-side draft persisted to
localStorage, EXIF-driven image placement, snap-to-route via BRouter
(OSRM + linear fallback) and Swisstopo profile.json elevation
enrichment that handles degenerate same-coord segments via the height
endpoint.

Filter init switched from a script-time snapshot of data.hikes (which
sporadically returned a one-hike subset during dev hydration and
locked the page to that single hike) to a post-mount \$effect.

Content under src/content/hikes/ intentionally not included (WIP).

package.json

@@ -1,11 +1,11 @@
 {
 	"name": "homepage",
-	"version": "1.70.2",
+	"version": "1.71.0",
 	"private": true,
 	"type": "module",
 	"scripts": {
 		"dev": "vite dev",
-		"prebuild": "bash scripts/subset-emoji-font.sh && pnpm exec vite-node scripts/generate-mystery-verses.ts && pnpm exec vite-node scripts/download-models.ts && pnpm exec vite-node scripts/generate-loyalty-cards.ts && pnpm exec vite-node scripts/generate-error-quotes.ts",
+		"prebuild": "bash scripts/subset-emoji-font.sh && pnpm exec vite-node scripts/generate-mystery-verses.ts && pnpm exec vite-node scripts/download-models.ts && pnpm exec vite-node scripts/generate-loyalty-cards.ts && pnpm exec vite-node scripts/generate-error-quotes.ts && pnpm exec vite-node scripts/build-hikes.ts",
 		"build": "vite build",
 		"postbuild": "pnpm exec vite-node scripts/build-error-page.ts",
 		"preview": "vite preview",
@@ -40,6 +40,7 @@
 		"@vitest/ui": "^4.1.2",
 		"bwip-js": "^4.10.1",
 		"jsdom": "^27.2.0",
+		"mdsvex": "^0.12.7",
 		"svelte": "^5.55.1",
 		"svelte-check": "^4.4.6",
 		"tslib": "^2.8.1",
@@ -59,6 +60,7 @@
 		"chart.js": "^4.5.1",
 		"chartjs-adapter-date-fns": "^3.0.0",
 		"date-fns": "^4.1.0",
+		"exifr": "^7.1.3",
 		"file-type": "^19.0.0",
 		"leaflet": "^1.9.4",
 		"mongoose": "^9.4.1",