fix(pitch-deck): close auth gaps, isolate finanzplan scenario access, enforce TS

D1: Remove /api/admin/fp-patch from PUBLIC_PATHS — it was returning live financial
data (fp_liquiditaet rows) to any unauthenticated caller; middleware admin gate now
applies as it does for all /api/admin/* paths.

D2: Add PITCH_ADMIN_SECRET bearer guard to POST /api/financial-model (create scenario)
and PUT /api/financial-model/assumptions (update assumptions) — any authenticated
investor could previously create/modify global financial model data.

D3: Add PITCH_ADMIN_SECRET bearer guard to POST /api/finanzplan/compute — any
investor could trigger a full DB recomputation across all fp_* tables. Also replace
String(error) in error response with a static message.

D4: GET /api/finanzplan/[sheetName] now ignores ?scenarioId= for non-admin callers;
investors always receive the default scenario only. Previously any investor could
enumerate UUIDs and read any scenario's financials including other investors' plans.

D9: Remove `name` from the non-admin /api/finanzplan response — scenario names like
"Wandeldarlehen v2" reveal internal versioning to investors.

D10: Remove hardcoded postgres://breakpilot:breakpilot123@localhost fallback from
lib/db.ts — missing DATABASE_URL now fails loudly instead of silently using stale
credentials that are committed to the repository.

D6: Fix all 4 TypeScript errors that were masked by ignoreBuildErrors:true; bump
tsconfig target to ES2018 (regex s flag in ChatFAB), type lang as 'de'|'en' in
chat route, add 'as string' assertion in adapter.ts. Remove ignoreBuildErrors:true
from next.config.js so future type errors fail the build rather than being silently
shipped.

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

pitch-deck/app/api/finanzplan/compute/route.ts

@@ -1,8 +1,12 @@
 import { NextRequest, NextResponse } from 'next/server'
 import pool from '@/lib/db'
 import { computeFinanzplan } from '@/lib/finanzplan/engine'
+import { validateAdminSecret } from '@/lib/auth'
 
 export async function POST(request: NextRequest) {
+  if (!validateAdminSecret(request)) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  }
   try {
     const body = await request.json().catch(() => ({}))
     const scenarioId = body.scenarioId
@@ -33,6 +37,6 @@ export async function POST(request: NextRequest) {
     })
   } catch (error) {
     console.error('Finanzplan compute error:', error)
-    return NextResponse.json({ error: String(error) }, { status: 500 })
+    return NextResponse.json({ error: 'Compute failed' }, { status: 500 })
   }
 }