Phase 2/3: Employees list/detail + mutation RPCs + action panels

- supabase/functions.sql, functions_2.sql: Postgres RPCs for every
  employee/position/reorg mutation (hire, terminate, transfer, promote,
  start/adjust/return karenz, change data, rehire, create position, staff
  internally, apply/undo reorg). Each resolves manager_id server-side,
  writes history + audit atomically, and enforces hr_admin via
  require_hr_admin() (backed by the existing RLS policy).
- actions/employees.ts, positions.ts, reorg.ts: Server Actions wrapping
  the RPCs, returning success/error for client-side toast handling.
- Employees list (search/filter/pagination) and detail (4 tabs: Stammdaten,
  Vertrag & Gehalt, Organisation, Historie) reading from employees_directory.
- 6 action slide-over panels: Transfer, Promote, Karenz (start/adjust/
  return), Daten aendern (person+contract diffing), Terminate (with direct-
  report reparenting warning + offboarding checklist), Rehire.
- lib/org.ts: shared division/department/team/location lookups.

Verified live: promote mutation updates salary, writes history/audit, and
the detail page reflects it after refresh, no console errors.

Note: the spec's Karenz-verwalten panel only covers employees already on
Karenz; added a start-Karenz mode (Karenzbeginn/geplante Rueckkehr) to
cover the Aktiv-employee case implied by the header button but not
specified in the panel list.

components/employees/tabs/HistorieTab.tsx

@@ -0,0 +1,35 @@
+import { actionBadgeStyle } from "@/lib/colors";
+import { fmtDate } from "@/lib/format";
+import type { Database } from "@/lib/supabase/types";
+
+type HistoryRow = Database["public"]["Tables"]["employee_history"]["Row"];
+
+export function HistorieTab({ history }: { history: HistoryRow[] }) {
+  const today = new Date().toISOString().slice(0, 10);
+
+  if (history.length === 0) {
+    return <p className="text-sm text-ink-muted">Keine Historieneinträge vorhanden.</p>;
+  }
+
+  return (
+    <ul className="flex flex-col divide-y divide-border">
+      {history.map((h) => {
+        const isFuture = h.event_date > today;
+        return (
+          <li key={h.id} className="py-3">
+            <div className="flex flex-wrap items-center gap-2">
+              <span className={`rounded-full px-2 py-0.5 text-xs font-semibold ${actionBadgeStyle(h.event_type)}`}>{h.event_type}</span>
+              <span className="text-sm text-ink-muted">{fmtDate(h.event_date)}</span>
+              {isFuture && (
+                <span className="rounded-full bg-warning-bg px-2 py-0.5 text-xs font-semibold text-warning-text">
+                  ⏱ zukünftig – wirksam ab {fmtDate(h.event_date)}
+                </span>
+              )}
+            </div>
+            <p className="mt-1 text-sm text-ink">{h.description}</p>
+          </li>
+        );
+      })}
+    </ul>
+  );
+}