Org assignment history, mobile support, and a correctness pass

Data model
- employee_assignments records org placement over time (valid_from/valid_to),
  written by a trigger on `employees` rather than inside each RPC: ~70
  `update employees` statements spread over fifteen migrations mean per-call
  bookkeeping would miss paths today and again with every future RPC. A
  partial unique index enforces the one-open-interval invariant the trigger
  relies on when closing the current row.
- The Organigramm gains a Stichtag (default today). Membership comes from
  entry/exit/karenz, past placement from the new history, future placement
  projected from pending_org_changes. Placements predating the migration are
  backfilled with today's values and flagged as such in the UI, since
  employee_history only ever stored free text and cannot be reconstructed.

Correctness
- Reports and exports silently truncated at PostgREST's 1000-row cap
  (db.max_rows); employee_history is already past it at ~800 staff. Every
  whole-table read now pages explicitly.
- XLSX date cells were a day early: ExcelJS converts a Date to an Excel
  serial straight off getTime(), so a Date built at local midnight lands on
  the previous day's serial in any positive-offset zone.
- Date handling is pinned to Europe/Vienna throughout, and date-only strings
  are formatted without a Date round-trip. The dashboard's YTD window was
  built by round-tripping a local Date through toISOString(), which shifted
  it a day early and dropped 31 December entirely.
- Export routes parsed measure/group/split/eventType with unchecked `as`
  casts, so an unknown value reached column headers as `undefined` and the
  Content-Disposition filename. Parsed against the label maps now, with the
  filename slugged as a backstop.
- toXlsx keyed columns by header text, silently dropping the second of any
  two columns sharing a name — split columns take their header from data.
- The org chart tree walks had no cycle guard; nothing in the schema forbids
  a manager_id cycle, and one would hang the tab rather than misreport.
- The login page reflected ?error= verbatim, letting anyone put arbitrary
  text on the real sign-in screen; messages are looked up by code now.
- React Flow needs elementsSelectable on, or it sets pointer-events:none on
  the whole node and the expand control stops responding.

UI
- Mobile: the shell was unusable below lg — a fixed 236px margin pushed
  content off-screen with no mobile navigation at all. The sidebar is now a
  drawer, dvh replaces vh, safe-area insets are honoured, inputs are 16px so
  iOS stops zooming on focus, and form grids stack.
- Org chart nodes redesigned: per-kind accent stripes and icons, vacant
  roles called out, expand control moved to the bottom edge carrying the
  child count.
- Pagination is windowed; it previously rendered one link per page (54 for
  the employee list, unbounded for the audit log).
- Positions page reduced to open positions with a single "Besetzen" action.
- The employee Organisation tab links into the org chart focused on that
  person, reusing the chart's existing search-match highlighting.

Also included, uncommitted until now
- Dependants, HR notes, academic titles, split address fields, position
  validity and role/employment fields, with their migrations and UI.
- Docker/compose deployment setup, data-model and security-review docs.

components/employees/tabs/StammdatenTab.tsx

@@ -1,28 +1,44 @@
+import { AngehoerigeSection } from "@/components/employees/AngehoerigeSection";
 import { fmtAge, fmtDate } from "@/lib/format";
 import type { Database } from "@/lib/supabase/types";
 
 type EmployeeRow = Database["public"]["Tables"]["employees"]["Row"];
 type Location = Database["public"]["Tables"]["locations"]["Row"];
+type Dependent = Database["public"]["Tables"]["employee_dependents"]["Row"];
 
-export function StammdatenTab({ employee, location }: { employee: EmployeeRow; location?: Location }) {
+function formatAddress(employee: EmployeeRow): string {
+  const cityLine = [employee.postal_code, employee.city].filter(Boolean).join(" ");
+  return [employee.address, cityLine].filter(Boolean).join(", ") || "–";
+}
+
+export function StammdatenTab({ employee, location, dependents }: { employee: EmployeeRow; location?: Location; dependents: Dependent[] }) {
+  // Defensive against a DB that hasn't received the title_prefix/title_suffix
+  // migration yet — select("*") simply omits unknown columns, so these can
+  // be undefined rather than the empty array the column default implies.
+  const titles = [...(employee.title_prefix ?? []), ...(employee.title_suffix ?? [])];
   const rows: [string, string][] = [
+    ["Titel", titles.length > 0 ? titles.join(", ") : "–"],
     ["Geburtsdatum", `${fmtDate(employee.birth_date)} (${fmtAge(employee.birth_date)} Jahre)`],
     ["SV-Nummer", employee.sv_nummer ?? "–"],
     ["Staatsbürgerschaft", employee.nationality],
     ["E-Mail", employee.email],
     ["Telefon", employee.phone ?? "–"],
     ["Standort", location ? `${location.name} (${location.country})` : "–"],
-    ["Adresse", employee.address ?? "–"],
+    ["Adresse", formatAddress(employee)],
+    ["Land", employee.address_country ?? "–"],
     ["Geschlecht", employee.gender === "m" ? "männlich" : "weiblich"],
   ];
   return (
-    <dl className="grid grid-cols-1 gap-x-8 gap-y-4 sm:grid-cols-2 lg:grid-cols-3">
-      {rows.map(([label, value]) => (
-        <div key={label}>
-          <dt className="text-xs font-semibold uppercase tracking-wide text-ink-muted">{label}</dt>
-          <dd className="mt-1 text-sm text-ink">{value}</dd>
-        </div>
-      ))}
-    </dl>
+    <div className="flex flex-col gap-6">
+      <dl className="grid grid-cols-1 gap-x-8 gap-y-4 sm:grid-cols-2 lg:grid-cols-3">
+        {rows.map(([label, value]) => (
+          <div key={label}>
+            <dt className="text-xs font-semibold uppercase tracking-wide text-ink-muted">{label}</dt>
+            <dd className="mt-1 text-sm text-ink">{value}</dd>
+          </div>
+        ))}
+      </dl>
+      <AngehoerigeSection employeeId={employee.id} dependents={dependents} />
+    </div>
   );
 }