feat(spa): detail-route auf prerender + ssr=true

Lokaler override des global ssr=false. entries() liest aus
snapshot/output/index.json, load() pro-slug aus posts/<slug>.json.
runtime-fallback bleibt fuer slugs ausserhalb des snapshots.

@types/node als devDependency ergaenzt, da node:fs/promises-Typen
fuer den SSR-Pfad benoetigt werden.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/package.json

@@ -20,6 +20,7 @@
 		"@sveltejs/kit": "^2.57.0",
 		"@sveltejs/vite-plugin-svelte": "^7.0.0",
 		"@testing-library/svelte": "^5.3.1",
+		"@types/node": "^25.6.0",
 		"jsdom": "^29.0.2",
 		"svelte": "^5.55.2",
 		"svelte-check": "^4.4.6",

app/src/routes/[...slug]/+page.ts

@@ -1,21 +1,78 @@
-import { error, redirect } from '@sveltejs/kit';
-import { parseLegacyUrl, canonicalPostPath } from '$lib/url/legacy';
-import type { PageLoad } from './$types';
+import { error, redirect } from '@sveltejs/kit'
+import { parseLegacyUrl, canonicalPostPath } from '$lib/url/legacy'
+import type { EntryGenerator, PageLoad } from './$types'
+import { browser } from '$app/environment'
+
+export const ssr = true
+export const prerender = true
+export const trailingSlash = 'always'
+
+interface SnapshotIndex {
+  posts: Array<{ slug: string; lang: string; title: string }>
+}
+
+interface PostJson {
+  slug: string
+  event_id: string
+  created_at: number
+  published_at: number
+  title: string
+  summary: string
+  lang: string
+  cover_image: { url: string; alt?: string; width?: number; height?: number; mime?: string } | null
+  content_markdown: string
+  tags: string[]
+  naddr: string
+  habla_url: string
+  translations: Array<{ lang: string; slug: string; title: string }>
+}
+
+let cachedIndex: SnapshotIndex | undefined
+async function readIndex(): Promise<SnapshotIndex> {
+  if (cachedIndex) return cachedIndex
+  const fs = await import('node:fs/promises')
+  const path = await import('node:path')
+  const dir = path.resolve('../snapshot/output')
+  const text = await fs.readFile(path.join(dir, 'index.json'), 'utf-8')
+  cachedIndex = JSON.parse(text) as SnapshotIndex
+  return cachedIndex
+}
+
+async function readPost(slug: string): Promise<PostJson | undefined> {
+  try {
+    const fs = await import('node:fs/promises')
+    const path = await import('node:path')
+    const dir = path.resolve('../snapshot/output')
+    const text = await fs.readFile(path.join(dir, 'posts', `${slug}.json`), 'utf-8')
+    return JSON.parse(text) as PostJson
+  } catch {
+    return undefined
+  }
+}
+
+export const entries: EntryGenerator = async () => {
+  const idx = await readIndex()
+  return idx.posts.map((p) => ({ slug: p.slug }))
+}
 
 export const load: PageLoad = async ({ url }) => {
-	const pathname = url.pathname;
+  const pathname = url.pathname
 
-	// Legacy-Form /YYYY/MM/DD/<dtag>.html/ → Redirect auf /<dtag>/
-	const legacyDtag = parseLegacyUrl(pathname);
+  const legacyDtag = parseLegacyUrl(pathname)
   if (legacyDtag) {
-		throw redirect(301, canonicalPostPath(legacyDtag));
+    throw redirect(301, canonicalPostPath(legacyDtag))
   }
 
-	// Kanonisch: /<dtag>/ — erster Segment des Pfades.
-	const segments = pathname.replace(/^\/+|\/+$/g, '').split('/');
+  const segments = pathname.replace(/^\/+|\/+$/g, '').split('/')
   if (segments.length !== 1 || !segments[0]) {
-		throw error(404, 'Seite nicht gefunden');
+    throw error(404, 'Seite nicht gefunden')
+  }
+  const dtag = decodeURIComponent(segments[0])
+
+  if (!browser) {
+    const snapshot = await readPost(dtag)
+    if (snapshot) return { dtag, snapshot }
   }
 
-	return { dtag: decodeURIComponent(segments[0]) };
-};
+  return { dtag, snapshot: null }
+}