feat: enhance forms with decimal formatting and validation

- Updated CustomersPage.vue to use decimalString for standard discount percent.
- Enhanced IncomingInvoicesPage.vue to format item quantities, unit prices, and tax rates using decimalString.
- Improved ItemsPage.vue with new supplier price management and decimal formatting for prices.
- Modified OrganizationSetupPage.vue to use a dropdown for default tax rates and ensure numeric input for payment days.
- Updated OutgoingInvoicesPage.vue to apply decimal formatting for customer discounts and item details.
- Enhanced PriceImportsPage.vue to include additional fields in the import format.
- Improved PriceRulesPage.vue to use decimal input for markup percentages.
- Updated QuotesPage.vue to apply decimal formatting for customer discounts and item details.
- Enhanced SuppliersPage.vue to use decimal input for standard discount percent.
- Added a new SQL migration to set default unit for items to 'Stck'.
- Introduced format.ts for centralized decimal and currency formatting utilities.

web-frontend/src/views/CashDiscountTermsPage.vue

@@ -3,6 +3,7 @@ import { onMounted, reactive, ref, watch } from "vue";
 import { apiDelete, apiGet, apiPost, apiPut } from "../api";
 import FormStatus from "../components/FormStatus.vue";
 import PageHeader from "../components/PageHeader.vue";
+import { decimalString } from "../format";
 import { liveUpdateState } from "../realtime";
 import type { CashDiscountTerm } from "../types";
 
@@ -53,9 +54,13 @@ function select(term: CashDiscountTerm) {
 }
 
 async function save() {
+  const payload = {
+    ...form,
+    discount_percent: decimalString(form.discount_percent)
+  };
   const result = selectedId.value
-    ? await apiPut<CashDiscountTerm>(`/api/v1/cash-discount-terms/${selectedId.value}`, form)
-    : await apiPost<CashDiscountTerm>("/api/v1/cash-discount-terms", form);
+    ? await apiPut<CashDiscountTerm>(`/api/v1/cash-discount-terms/${selectedId.value}`, payload)
+    : await apiPost<CashDiscountTerm>("/api/v1/cash-discount-terms", payload);
   status.value = result.ok ? "Skonto-Regel gespeichert." : result.message;
   kind.value = result.ok ? "success" : "error";
   if (result.ok) { selectedId.value = result.data.id; await load(); }
@@ -74,7 +79,7 @@ watch(() => liveUpdateState.revision, load);
 </script>
 
 <template>
-  <PageHeader title="Skonto" description="Zahlungsbedingungen für Kunden, Lieferanten und Belege." />
+  <PageHeader title="Skonto-Regeln" description="Zahlungsbedingungen für Kunden, Lieferanten und Belege." />
   <div class="workspace-split">
     <section class="panel list-panel">
       <div class="section-title"><h2>Regeln</h2><button type="button" @click="createNew">Neu</button></div>
@@ -90,7 +95,7 @@ watch(() => liveUpdateState.revision, load);
         <div class="form-grid">
           <label class="field"><span>Code</span><input v-model="form.code" required /></label>
           <label class="field"><span>Name</span><input v-model="form.name" required /></label>
-          <label class="field"><span>Skonto %</span><input v-model="form.discount_percent" type="number" min="0" max="100" step="0.01" required /></label>
+          <label class="field"><span>Skonto %</span><input v-model="form.discount_percent" inputmode="decimal" required /></label>
           <label class="field"><span>Skontofrist Tage</span><input v-model="form.discount_days" type="number" min="0" required /></label>
           <label class="field"><span>Nettoziel Tage</span><input v-model="form.net_days" type="number" min="0" /></label>
           <label class="field"><span>Gültig ab</span><input v-model="form.valid_from" type="date" /></label>