Phase 1: project foundation for Alpenwerk HR

Scaffolds the Next.js 16 / TypeScript strict / Tailwind v3 app per
NEXTJS_REBUILD_SUPERPROMPT.md, and implements the Foundation slice from
the Phase 1 plan:

- Corrected Supabase schema (supabase/schema.sql): org units, employees,
  history, positions, hire drafts, saved reports, audit log, reorg
  scenarios, role-based profiles, salary-masking view, RLS policies,
  auto-derivation triggers, position-number generator.
- Seed script (supabase/seed.ts): ~800 realistic Austrian employees across
  9 divisions / 16 departments / 35 teams, history, 8 open positions, and
  hr_admin/manager test accounts.
- Supabase clients (lib/supabase/*), design tokens (tailwind.config.ts),
  format/color helpers (lib/format.ts, lib/colors.ts).
- Shared UI kit (components/ui): Avatar, StatusChip, Toast, Modal,
  SlideOver, SegmentedControl, Lookup.
- Auth (login page, Server Actions) and proxy.ts (Next 16's replacement
  for middleware) guarding the authenticated route group.
- Shell (Sidebar, Topbar, NewHireButton stub) and the Dashboard page,
  reading live data via employees_directory.

Employees list/detail, hire wizard, action panels, org chart, positions,
reports, and audit log are deferred to later phases per the plan.

lib/colors.ts

@@ -0,0 +1,63 @@
+import type { EmploymentStatus } from "./supabase/types";
+
+const AVATAR_PALETTE = [
+  "#d6046e",
+  "#00666d",
+  "#5c2e91",
+  "#835b00",
+  "#0e700e",
+  "#b0035a",
+  "#2b6cb0",
+  "#a30354",
+];
+
+// Stable per-employee avatar color when employees.avatar_color isn't set.
+export function avatarColorFor(seed: string): string {
+  let hash = 0;
+  for (let i = 0; i < seed.length; i++) {
+    hash = (hash << 5) - hash + seed.charCodeAt(i);
+    hash |= 0;
+  }
+  return AVATAR_PALETTE[Math.abs(hash) % AVATAR_PALETTE.length];
+}
+
+export const STATUS_STYLES: Record<EmploymentStatus, string> = {
+  Aktiv: "bg-success-bg text-success-text",
+  Karenz: "bg-warning-bg text-warning-text",
+  Geplant: "bg-brand-100 text-brand-700",
+  Ausgetreten: "bg-danger-bg text-danger-text",
+};
+
+type ColorCategory = "success" | "danger" | "warning" | "info" | "purple" | "brand";
+
+const CATEGORY_STYLES: Record<ColorCategory, string> = {
+  success: "bg-success-bg text-success-text",
+  danger: "bg-danger-bg text-danger-text",
+  warning: "bg-warning-bg text-warning-text",
+  info: "bg-info-bg text-info-text",
+  purple: "bg-purple-bg text-purple-text",
+  brand: "bg-brand-100 text-brand-700",
+};
+
+// Audit-log / activity-feed action -> badge color, per the action list in
+// supabase/schema.sql's audit_log comment.
+const ACTION_CATEGORY: Record<string, ColorCategory> = {
+  Neueinstellung: "success",
+  Wiedereinstellung: "success",
+  Rückkehr: "success",
+  Austritt: "danger",
+  Versetzung: "info",
+  Ausschreibung: "info",
+  "Interne Besetzung": "info",
+  Beförderung: "purple",
+  Reorganisation: "purple",
+  "Reorganisation rückgängig": "purple",
+  Karenz: "warning",
+  Vertragsänderung: "warning",
+  Stammdatenänderung: "warning",
+  Gehaltsanpassung: "warning",
+};
+
+export function actionBadgeStyle(action: string): string {
+  return CATEGORY_STYLES[ACTION_CATEGORY[action] ?? "brand"];
+}