feat: Finanzplan Phase 1-4 — DB + Engine + API + Spreadsheet-UI

Phase 1: DB-Schema (12 fp_* Tabellen) + Excel-Import (332 Zeilen importiert)
Phase 2: Compute Engine (Personal, Invest, Umsatz, Material, Betrieblich, Liquiditaet, GuV)
Phase 3: API (/api/finanzplan/ — GET sheets, PUT cells, POST compute)
Phase 4: Spreadsheet-UI (FinanzplanSlide als Annex mit Tab-Leiste, editierbarem Grid, Jahres-Navigation)

Zusaetzlich:
- Gruendungsdatum verschoben: Feb→Aug 2026 (DB + Personalkosten)
- Neue Preisstaffel: Startup/<10 MA ab 3.600 EUR/Jahr (14-Tage-Test, Kreditkarte)
- Competition-Slide: Pricing-Tiers aktualisiert

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pitch-deck/app/api/finanzplan/[sheetName]/route.ts

@@ -0,0 +1,100 @@
+import { NextRequest, NextResponse } from 'next/server'
+import pool from '@/lib/db'
+
+const TABLE_MAP: Record<string, string> = {
+  kunden: 'fp_kunden',
+  kunden_summary: 'fp_kunden_summary',
+  umsatzerloese: 'fp_umsatzerloese',
+  materialaufwand: 'fp_materialaufwand',
+  personalkosten: 'fp_personalkosten',
+  betriebliche: 'fp_betriebliche_aufwendungen',
+  investitionen: 'fp_investitionen',
+  sonst_ertraege: 'fp_sonst_ertraege',
+  liquiditaet: 'fp_liquiditaet',
+  guv: 'fp_guv',
+}
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ sheetName: string }> }
+) {
+  const { sheetName } = await params
+  const table = TABLE_MAP[sheetName]
+  if (!table) {
+    return NextResponse.json({ error: `Unknown sheet: ${sheetName}` }, { status: 400 })
+  }
+
+  const scenarioId = request.nextUrl.searchParams.get('scenarioId')
+
+  try {
+    let query = `SELECT * FROM ${table}`
+    const params: string[] = []
+
+    if (scenarioId) {
+      query += ' WHERE scenario_id = $1'
+      params.push(scenarioId)
+    } else {
+      query += ' WHERE scenario_id = (SELECT id FROM fp_scenarios WHERE is_default = true LIMIT 1)'
+    }
+    query += ' ORDER BY sort_order'
+
+    const { rows } = await pool.query(query, params)
+    return NextResponse.json({ sheet: sheetName, rows })
+  } catch (error) {
+    return NextResponse.json({ error: String(error) }, { status: 500 })
+  }
+}
+
+export async function PUT(
+  request: NextRequest,
+  { params }: { params: Promise<{ sheetName: string }> }
+) {
+  const { sheetName } = await params
+  const table = TABLE_MAP[sheetName]
+  if (!table) {
+    return NextResponse.json({ error: `Unknown sheet: ${sheetName}` }, { status: 400 })
+  }
+
+  try {
+    const body = await request.json()
+    const { rowId, updates } = body // updates: { field: value } or { m3: 1500 } for monthly values
+
+    if (!rowId) {
+      return NextResponse.json({ error: 'rowId required' }, { status: 400 })
+    }
+
+    // Check if updating monthly values (JSONB) or scalar fields
+    const monthlyKeys = Object.keys(updates).filter(k => k.startsWith('m') && !isNaN(parseInt(k.substring(1))))
+    const scalarKeys = Object.keys(updates).filter(k => !k.startsWith('m') || isNaN(parseInt(k.substring(1))))
+
+    if (monthlyKeys.length > 0) {
+      // Update specific months in the values JSONB
+      const jsonbSet = monthlyKeys.map(k => `'${k}', '${updates[k]}'::jsonb`).join(', ')
+      const valuesCol = sheetName === 'personalkosten' ? 'values_brutto' : 'values'
+      // Use jsonb_set for each key
+      let updateSql = `UPDATE ${table} SET `
+      const setClauses: string[] = []
+      for (const k of monthlyKeys) {
+        setClauses.push(`${valuesCol} = jsonb_set(${valuesCol}, '{${k}}', '${updates[k]}')`)
+      }
+      setClauses.push(`updated_at = NOW()`)
+      updateSql += setClauses.join(', ') + ` WHERE id = $1`
+      await pool.query(updateSql, [rowId])
+    }
+
+    if (scalarKeys.length > 0) {
+      // Update scalar columns directly
+      const setClauses = scalarKeys.map((k, i) => `${k} = $${i + 2}`).join(', ')
+      await pool.query(
+        `UPDATE ${table} SET ${setClauses}, updated_at = NOW() WHERE id = $1`,
+        [rowId, ...scalarKeys.map(k => updates[k])]
+      )
+    }
+
+    // Return updated row
+    const { rows } = await pool.query(`SELECT * FROM ${table} WHERE id = $1`, [rowId])
+    return NextResponse.json({ updated: rows[0] })
+  } catch (error) {
+    return NextResponse.json({ error: String(error) }, { status: 500 })
+  }
+}