fix(preview): return fp_scenarios key so version-specific scenario is resolved in admin preview

The preview-data API was returning `fm_scenarios` but PitchDeck reads
`data.fp_scenarios`, so fpBaseScenarioId was always null and the
Finanzplan slide fell back to the global default scenario (Base Case 200k)
instead of the version's assigned scenario (e.g. 1 Mio. Euro Base).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pitch-deck/app/api/preview-data/[versionId]/route.ts

@@ -49,7 +49,7 @@ export async function GET(request: NextRequest, ctx: Ctx) {
     metrics: map.metrics || [],
     funding: (map.funding || [])[0] || null,
     products: map.products || [],
-    fm_scenarios: map.fm_scenarios || [],
+    fp_scenarios: map.fm_scenarios || [],
     fm_assumptions: map.fm_assumptions || [],
     _version: { name: ver.rows[0].name, status: ver.rows[0].status },
   })