Self-hosted employee directory (in-app management + CSV import)

Most sites have no external HR database, so add a self-hosted directory mode.

- New employee_directory_mode setting: 'external' (default; read a separate HR
  DB, unchanged) or 'selfhosted' (app-owned table).
- DirectoryEmployee model + directoryemployees table (migration 7d16). to_dict
  emits the same keys the external contract uses (SSO/First_Name/...), so both
  modes share one response shape and the frontend is unchanged.
- Employee search / single / batch lookup branch on the mode.
- Self-hosted-only management endpoints: list, create, update, delete, and CSV
  import (upsert by SSO). Guarded so they only work in self-hosted mode.
- EmployeeDirectory.vue management page (Settings > Locations & Organization):
  table + search + pagination, add/edit/delete, CSV import (file or paste).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/views/settings/settingsNav.js

@@ -1,7 +1,7 @@
 // Shared settings navigation catalog.
 // Used by SettingsLayout (left rail) and SettingsIndex (landing overview) so the
 // grouping lives in one place.
-import { Factory, MapPin, Tag, Package, Droplets, Monitor, MonitorSmartphone, Laptop, Cog, Building, Globe, Link, Settings, FileText, Users, Puzzle, Bell, Network, Home, Wrench, Printer, Router, Palette, SlidersHorizontal } from 'lucide-vue-next'
+import { Factory, MapPin, Tag, Package, Droplets, Monitor, MonitorSmartphone, Laptop, Cog, Building, Globe, Link, Settings, FileText, Users, Puzzle, Bell, Network, Home, Wrench, Printer, Router, Palette, SlidersHorizontal, Contact } from 'lucide-vue-next'
 
 export const settingsGroups = [
   {
@@ -48,6 +48,7 @@ export const settingsGroups = [
   {
     title: 'Locations & Organization',
     cards: [
+      { to: '/settings/employeedirectory', icon: Contact, title: 'Employee Directory', description: 'Manage the self-hosted people directory (add/edit/import); read-only in external HR mode' },
       { to: '/settings/locations', icon: MapPin, title: 'Locations', description: 'Manage physical locations and sites' },
       { to: '/settings/locationtypes', icon: Tag, title: 'Location Types', description: 'Manage location types + colors' },
       { to: '/settings/businessunits', icon: Building, title: 'Business Units', description: 'Manage organizational units' },