feat(pitch-deck): Gewerbesteuer formula + BG/Marketing/Telefon engine formulas + tooltips

Engine:
- Gewerbesteuer (F): 12.25% of monthly profit (only when positive)
- Berufsgenossenschaft (F): 2.77% of brutto payroll
- Allgemeine Marketingkosten (F): 10% of revenue
- Internet/Mobilfunk (F): Headcount × 50 EUR/Mon

UI: Tooltip for Gewerbesteuer formula added.

DB changes (production):
- Gewerbesteuer: (M) → (F), auto-calculated
- Rechtsanwalt/Datenschutz: new hire Oct 2026, 7500 EUR brutto
- Beratung & Services: new revenue line (5k→30k/Mon)
- Investitionen: Home Office 2500 EUR per new hire
- Marketing Videos moved to marketing category
- Bank → Bank-/Kreditkartengebühren
- Jahresabschluss costs filled (1000-2000 EUR/year)

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

pitch-deck/lib/finanzplan/engine.ts

@@ -304,6 +304,29 @@ export async function computeFinanzplan(pool: Pool, scenarioId: string): Promise
     abrBetrieb.values = totalAfa
   }
 
+  // Gewerbesteuer (F): 12.25% of monthly profit (only when positive)
+  // Monthly profit = Revenue - Material - Personnel - AfA - other opex (excl. taxes)
+  const gewStRow = betrieb.find(r => r.row_label.includes('Gewerbesteuer'))
+  if (gewStRow) {
+    const nonTaxOpex = betrieb.filter(r =>
+      r.category !== 'steuern' && r.category !== 'personal' && r.category !== 'abschreibungen' &&
+      !r.is_sum_row && !r.row_label.includes('Summe') && !r.row_label.includes('SUMME')
+    )
+    const computed = emptyMonthly()
+    for (let m = 1; m <= MONTHS; m++) {
+      const rev = totalRevenue[`m${m}`] || 0
+      const mat = totalMaterial[`m${m}`] || 0
+      const pers = totalPersonal[`m${m}`] || 0
+      const afa = totalAfa[`m${m}`] || 0
+      let opex = 0
+      for (const r of nonTaxOpex) { opex += r.values[`m${m}`] || 0 }
+      const profit = rev - mat - pers - afa - opex
+      computed[`m${m}`] = profit > 0 ? Math.round(profit * 0.1225) : 0
+    }
+    await pool.query('UPDATE fp_betriebliche_aufwendungen SET values = $1 WHERE id = $2', [JSON.stringify(computed), gewStRow.id])
+    gewStRow.values = computed
+  }
+
   // Compute category sums
   const categories = ['steuern', 'versicherungen', 'besondere', 'marketing', 'sonstige']
   for (const cat of categories) {