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.

lib/supabase/types.ts

@@ -281,6 +281,20 @@ export type Database = {
         };
       };
     };
-    Functions: Record<string, never>;
+    Functions: {
+      hire_employee: { Args: { payload: Record<string, unknown> }; Returns: string };
+      terminate_employee: { Args: { payload: Record<string, unknown> }; Returns: void };
+      transfer_employee: { Args: { payload: Record<string, unknown> }; Returns: void };
+      promote_employee: { Args: { payload: Record<string, unknown> }; Returns: void };
+      start_karenz: { Args: { payload: Record<string, unknown> }; Returns: void };
+      adjust_karenz_return: { Args: { payload: Record<string, unknown> }; Returns: void };
+      record_karenz_return: { Args: { payload: Record<string, unknown> }; Returns: void };
+      change_employee_data: { Args: { payload: Record<string, unknown> }; Returns: void };
+      rehire_employee: { Args: { payload: Record<string, unknown> }; Returns: void };
+      create_position: { Args: { payload: Record<string, unknown> }; Returns: string };
+      staff_position_internally: { Args: { payload: Record<string, unknown> }; Returns: void };
+      apply_reorg: { Args: { payload: Record<string, unknown> }; Returns: string };
+      undo_reorg: { Args: { payload: Record<string, unknown> }; Returns: void };
+    };
   };
 };