Migrate omsorgapp to browser SPA, add Docker/CI build setup

- omsorgapp: drop Electron, run as a plain Vite/React browser app; refresh
  token moves to an HttpOnly cookie (omsorgCore), CORS added for the new
  browser origin, document download/preview switched to Blob-based browser
  APIs.
- Add Dockerfiles for omsorgCore, omsorgapp, and omsorgWeb, a docker-compose.yml
  wiring Postgres/MySQL/all three apps together, and a Gitea Actions workflow
  that builds and pushes images to the repo's container registry on push to
  main and on version tags.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

omsorgapp/src/modules/employees/ContractForm.jsx

@@ -0,0 +1,159 @@
+import OmsorgButton from "../../components/ui/OmsorgButton";
+import { useValueListItems } from "../../app/useValueListItems";
+
+export const emptyContractForm = {
+  contractType: "",
+  startDate: "",
+  endDate: "",
+  status: "",
+  weeklyHours: "",
+  hourlyWage: "",
+  allowancesDescription: "",
+  overtimeRules: "",
+  vacationDaysPerYear: "",
+  probationPeriodMonths: "",
+};
+
+export function contractToFormValues(contract) {
+  return {
+    contractType: contract.contractType ?? "",
+    startDate: contract.startDate ?? "",
+    endDate: contract.endDate ?? "",
+    status: contract.status ?? "",
+    weeklyHours: contract.weeklyHours ?? "",
+    hourlyWage: contract.hourlyWage ?? "",
+    allowancesDescription: contract.allowancesDescription ?? "",
+    overtimeRules: contract.overtimeRules ?? "",
+    vacationDaysPerYear: contract.vacationDaysPerYear ?? "",
+    probationPeriodMonths: contract.probationPeriodMonths ?? "",
+  };
+}
+
+export function contractFormToPayload(form, { employeeId, includeStatus = false } = {}) {
+  const payload = {
+    contractType: form.contractType,
+    employeeId,
+    facilityId: null,
+    startDate: form.startDate,
+    endDate: form.endDate || null,
+    weeklyHours: form.weeklyHours === "" ? null : Number(form.weeklyHours),
+    hourlyWage: form.hourlyWage === "" ? null : Number(form.hourlyWage),
+    allowancesDescription: form.allowancesDescription.trim() || null,
+    overtimeRules: form.overtimeRules.trim() || null,
+    vacationDaysPerYear: form.vacationDaysPerYear === "" ? null : Number(form.vacationDaysPerYear),
+    probationPeriodMonths: form.probationPeriodMonths === "" ? null : Number(form.probationPeriodMonths),
+  };
+
+  if (includeStatus) {
+    payload.status = form.status;
+  }
+
+  return payload;
+}
+
+export default function ContractForm({ form, onChange, includeStatus = false }) {
+  const { items: contractTypes } = useValueListItems("ContractType");
+  const { items: contractStatuses } = useValueListItems("ContractStatus");
+
+  function updateField(field) {
+    return (event) => onChange({ ...form, [field]: event.target.value });
+  }
+
+  return (
+    <div className="form-grid">
+      <label className="form-field">
+        <span>Vertragstyp *</span>
+        <select value={form.contractType} onChange={updateField("contractType")} required>
+          <option value="">— auswählen —</option>
+          {contractTypes.map((option) => (
+            <option key={option.id} value={option.value}>
+              {option.value}
+            </option>
+          ))}
+        </select>
+      </label>
+
+      {includeStatus && (
+        <label className="form-field">
+          <span>Status</span>
+          <select value={form.status} onChange={updateField("status")}>
+            {contractStatuses.map((option) => (
+              <option key={option.id} value={option.value}>
+                {option.value}
+              </option>
+            ))}
+          </select>
+        </label>
+      )}
+
+      <div className="form-row">
+        <label className="form-field">
+          <span>Beginn *</span>
+          <input type="date" value={form.startDate} onChange={updateField("startDate")} required />
+        </label>
+
+        <label className="form-field">
+          <span>Ende</span>
+          <input type="date" value={form.endDate} onChange={updateField("endDate")} />
+        </label>
+      </div>
+
+      <div className="form-row">
+        <label className="form-field">
+          <span>Arbeitszeit (Std./Woche)</span>
+          <input type="number" min="0" step="0.5" value={form.weeklyHours} onChange={updateField("weeklyHours")} />
+        </label>
+
+        <label className="form-field">
+          <span>Stundenlohn (€)</span>
+          <input type="number" min="0" step="0.01" value={form.hourlyWage} onChange={updateField("hourlyWage")} />
+        </label>
+      </div>
+
+      <label className="form-field">
+        <span>Zuschläge</span>
+        <input value={form.allowancesDescription} onChange={updateField("allowancesDescription")} />
+      </label>
+
+      <label className="form-field">
+        <span>Überstundenregelung</span>
+        <input value={form.overtimeRules} onChange={updateField("overtimeRules")} />
+      </label>
+
+      <div className="form-row">
+        <label className="form-field">
+          <span>Urlaubsanspruch (Tage/Jahr)</span>
+          <input
+            type="number"
+            min="0"
+            value={form.vacationDaysPerYear}
+            onChange={updateField("vacationDaysPerYear")}
+          />
+        </label>
+
+        <label className="form-field">
+          <span>Probezeit (Monate)</span>
+          <input
+            type="number"
+            min="0"
+            value={form.probationPeriodMonths}
+            onChange={updateField("probationPeriodMonths")}
+          />
+        </label>
+      </div>
+    </div>
+  );
+}
+
+export function FormActions({ onCancel, isSaving, submitLabel }) {
+  return (
+    <div className="form-actions">
+      <OmsorgButton variant="secondary" type="button" onClick={onCancel} disabled={isSaving}>
+        Abbrechen
+      </OmsorgButton>
+      <OmsorgButton type="submit" disabled={isSaving}>
+        {isSaving ? "Speichert..." : submitLabel}
+      </OmsorgButton>
+    </div>
+  );
+}