Phase 3: Hire wizard, draft resume, and two real SQL bugfixes

- components/hire/: 4-step Hire Wizard (Person/Position/Vertrag/
  Zusammenfassung) matching sec4.4, with a HireWizardProvider context so it
  can be opened both from the global "+ Neueinstellung" button and from a
  "Fortsetzen" link on a saved draft.
- actions/hireDrafts.ts: save/delete hire_drafts (owner-scoped RLS already
  in place from Phase 1). Dashboard now shows the "Entwuerfe" card the
  Phase 1 plan deferred, since the wizard it depends on now exists.
- lib/positions.ts: shared open-positions loader (position number, org
  breadcrumb, resolved manager name) used by both the wizard and (later)
  the Positions page.

Two real bugs found via live testing and fixed in supabase/functions.sql:
1. hire_employee/rehire_employee: a two-branch CASE returning bare string
   literals defaults to `text`, not the target enum, so `status = case
   when ... then 'Geplant' else 'Aktiv' end` failed against the
   employment_status column. Fixed with an explicit ::employment_status
   cast on the whole CASE expression.
2. Postgres precedence gotcha: ->> and || sit at the *same* precedence
   tier and left-associate, so `payload->>'first_name' || ' ' ||
   payload->>'last_name'` does not group the way it reads - it tries to
   apply ->> to an intermediate text value and fails with "operator does
   not exist: text ->> unknown". Fixed by parenthesizing every ->>'...'
   expression that participates in a || chain.

Also fixed: hire_employee referenced v_position.title outside the branch
that assigns v_position, raising "record not assigned" whenever a hire
wasn't tied to a position_id; extracted a v_job_title variable instead.

Verified live end-to-end: wizard search -> select position -> submit
creates the employee, closes the position, and writes matching
employee_history + audit_log rows atomically.

supabase/functions.sql

@@ -74,6 +74,7 @@ declare
   v_team_id uuid;
   v_division_id uuid;
   v_position record;
+  v_job_title text;
   v_email text;
   v_manager uuid;
 begin
@@ -86,9 +87,11 @@ begin
     end if;
     v_team_id := v_position.team_id;
     v_division_id := v_position.division_id;
+    v_job_title := coalesce(payload->>'job_title', v_position.title);
   else
     v_team_id := (payload->>'team_id')::uuid;
     select division_id into v_division_id from teams t join departments d on d.id = t.department_id where t.id = v_team_id;
+    v_job_title := payload->>'job_title';
   end if;
 
   v_manager := resolve_manager_for(v_team_id, false, v_division_id);
@@ -103,7 +106,7 @@ begin
     payload->>'first_name', payload->>'last_name', (payload->>'gender')::gender_type,
     (payload->>'birth_date')::date, payload->>'sv_nummer', coalesce(payload->>'nationality', 'Österreich'),
     v_email, payload->>'phone',
-    v_team_id, v_division_id, coalesce(payload->>'job_title', v_position.title), (payload->>'location_id')::uuid,
+    v_team_id, v_division_id, v_job_title, (payload->>'location_id')::uuid,
     v_manager, 3, false,
     coalesce((payload->>'employment_type')::employment_type, 'Vollzeit'),
     coalesce((payload->>'weekly_hours')::numeric, 38.5),
@@ -112,7 +115,7 @@ begin
     nullif(payload->>'contract_end_date', '')::date,
     coalesce((payload->>'paygrade')::paygrade_type, 'B'),
     coalesce((payload->>'source')::source_type, 'Extern'),
-    case when (payload->>'entry_date')::date > current_date then 'Geplant' else 'Aktiv' end,
+    (case when (payload->>'entry_date')::date > current_date then 'Geplant' else 'Aktiv' end)::employment_status,
     (payload->>'entry_date')::date
   ) returning id into v_id;
 
@@ -122,10 +125,10 @@ begin
   end if;
 
   insert into employee_history (employee_id, event_date, event_type, description)
-    values (v_id, (payload->>'entry_date')::date, 'Eintritt', 'Eintritt als ' || coalesce(payload->>'job_title', v_position.title));
+    values (v_id, (payload->>'entry_date')::date, 'Eintritt', 'Eintritt als ' || v_job_title);
 
   insert into audit_log (actor_user_id, actor_name, action, target_label, target_employee_id, details)
-    values (auth.uid(), current_actor_name(), 'Neueinstellung', payload->>'first_name' || ' ' || payload->>'last_name', v_id, 'Eintritt am ' || (payload->>'entry_date'));
+    values (auth.uid(), current_actor_name(), 'Neueinstellung', (payload->>'first_name') || ' ' || (payload->>'last_name'), v_id, 'Eintritt am ' || (payload->>'entry_date'));
 
   return v_id;
 end;
@@ -376,7 +379,7 @@ begin
   v_manager := resolve_manager_for(v_team_id, v_is_lead, v_division_id);
 
   update employees set
-    status = case when v_rehire_date > current_date then 'Geplant' else 'Aktiv' end,
+    status = (case when v_rehire_date > current_date then 'Geplant' else 'Aktiv' end)::employment_status,
     entry_date = v_rehire_date,
     exit_date = null,
     exit_reason = null,