Org assignment history, mobile support, and a correctness pass

Data model
- employee_assignments records org placement over time (valid_from/valid_to),
  written by a trigger on `employees` rather than inside each RPC: ~70
  `update employees` statements spread over fifteen migrations mean per-call
  bookkeeping would miss paths today and again with every future RPC. A
  partial unique index enforces the one-open-interval invariant the trigger
  relies on when closing the current row.
- The Organigramm gains a Stichtag (default today). Membership comes from
  entry/exit/karenz, past placement from the new history, future placement
  projected from pending_org_changes. Placements predating the migration are
  backfilled with today's values and flagged as such in the UI, since
  employee_history only ever stored free text and cannot be reconstructed.

Correctness
- Reports and exports silently truncated at PostgREST's 1000-row cap
  (db.max_rows); employee_history is already past it at ~800 staff. Every
  whole-table read now pages explicitly.
- XLSX date cells were a day early: ExcelJS converts a Date to an Excel
  serial straight off getTime(), so a Date built at local midnight lands on
  the previous day's serial in any positive-offset zone.
- Date handling is pinned to Europe/Vienna throughout, and date-only strings
  are formatted without a Date round-trip. The dashboard's YTD window was
  built by round-tripping a local Date through toISOString(), which shifted
  it a day early and dropped 31 December entirely.
- Export routes parsed measure/group/split/eventType with unchecked `as`
  casts, so an unknown value reached column headers as `undefined` and the
  Content-Disposition filename. Parsed against the label maps now, with the
  filename slugged as a backstop.
- toXlsx keyed columns by header text, silently dropping the second of any
  two columns sharing a name — split columns take their header from data.
- The org chart tree walks had no cycle guard; nothing in the schema forbids
  a manager_id cycle, and one would hang the tab rather than misreport.
- The login page reflected ?error= verbatim, letting anyone put arbitrary
  text on the real sign-in screen; messages are looked up by code now.
- React Flow needs elementsSelectable on, or it sets pointer-events:none on
  the whole node and the expand control stops responding.

UI
- Mobile: the shell was unusable below lg — a fixed 236px margin pushed
  content off-screen with no mobile navigation at all. The sidebar is now a
  drawer, dvh replaces vh, safe-area insets are honoured, inputs are 16px so
  iOS stops zooming on focus, and form grids stack.
- Org chart nodes redesigned: per-kind accent stripes and icons, vacant
  roles called out, expand control moved to the bottom edge carrying the
  child count.
- Pagination is windowed; it previously rendered one link per page (54 for
  the employee list, unbounded for the audit log).
- Positions page reduced to open positions with a single "Besetzen" action.
- The employee Organisation tab links into the org chart focused on that
  person, reusing the chart's existing search-match highlighting.

Also included, uncommitted until now
- Dependants, HR notes, academic titles, split address fields, position
  validity and role/employment fields, with their migrations and UI.
- Docker/compose deployment setup, data-model and security-review docs.

app/api/export/report/route.ts

@@ -6,6 +6,16 @@ import {
   EVENT_GROUP_LABELS,
   GROUP_LABELS,
   MEASURE_LABELS,
+  parseEventDateParam,
+  parseEventGroupDimension,
+  parseEventSplitDimension,
+  parseEventType,
+  parseGroupDimension,
+  parseIsoDateParam,
+  parseMeasure,
+  parseMode,
+  parseSplitDimension,
+  sortKeysForDimension,
   sumValues,
   totalForRows,
   type EventGroupDimension,
@@ -14,8 +24,8 @@ import {
   type ReportRow,
 } from "@/lib/reports";
 import { loadEventHistory, loadOrgLookups, loadSnapshotEmployees } from "@/lib/reports-data";
+import { requireHrUser } from "@/lib/supabase/auth";
 import { createClient } from "@/lib/supabase/server";
-import type { HistoryEventType } from "@/lib/supabase/types";
 
 // Exports exactly the pivot table currently on screen (same mode/measure or
 // event-type/group/split/filters, read from the query string the client
@@ -23,19 +33,12 @@ import type { HistoryEventType } from "@/lib/supabase/types";
 // per split value if a split is active.
 export async function GET(request: NextRequest) {
   const supabase = await createClient();
-  const {
-    data: { user },
-  } = await supabase.auth.getUser();
-  if (!user) return NextResponse.json({ error: "Nicht angemeldet." }, { status: 401 });
-
-  const { data: profile } = await supabase.from("profiles").select("role, is_active").eq("id", user.id).maybeSingle();
-  if (profile?.role !== "hr" || profile?.is_active !== true) {
-    return NextResponse.json({ error: "Nicht berechtigt." }, { status: 403 });
-  }
+  const denied = await requireHrUser(supabase);
+  if (denied) return denied;
 
   const params = request.nextUrl.searchParams;
   const format = params.get("format") === "xlsx" ? "xlsx" : "csv";
-  const mode = params.get("mode") === "events" ? "events" : "snapshot";
+  const mode = parseMode(params.get("mode"));
   const { lookups } = await loadOrgLookups(supabase);
 
   let rows: ReportRow[];
@@ -43,24 +46,24 @@ export async function GET(request: NextRequest) {
   let filenameBase: string;
 
   if (mode === "events") {
-    const group = (params.get("group") as EventGroupDimension) || "event_type";
-    const split = (params.get("split") as EventGroupDimension) || null;
-    const eventType = (params.get("eventType") as HistoryEventType) || undefined;
+    const group = parseEventGroupDimension(params.get("group"));
+    const split = parseEventSplitDimension(params.get("split"));
+    const eventType = parseEventType(params.get("eventType"));
     const events = await loadEventHistory(supabase, {
-      eventType,
+      eventType: eventType ?? undefined,
       division: params.get("division") ?? undefined,
       location: params.get("location") ?? undefined,
-      from: params.get("from") ?? undefined,
-      to: params.get("to") ?? undefined,
+      from: parseEventDateParam(params.get("from")),
+      to: parseEventDateParam(params.get("to")),
     });
     rows = aggregateEvents(events, group, split, lookups);
     columns = eventReportColumns(rows, group, split, sumValues(rows));
     filenameBase = `ereignisse-${eventType ?? "alle"}-${group}`;
   } else {
-    const measure = (params.get("measure") as Measure) || "headcount";
-    const group = (params.get("group") as GroupDimension) || "division";
-    const split = (params.get("split") as GroupDimension) || null;
-    const asOf = params.get("asOf") ?? undefined;
+    const measure = parseMeasure(params.get("measure"));
+    const group = parseGroupDimension(params.get("group"));
+    const split = parseSplitDimension(params.get("split"));
+    const asOf = parseIsoDateParam(params.get("asOf"));
     const employees = await loadSnapshotEmployees(supabase, {
       division: params.get("division") ?? undefined,
       location: params.get("location") ?? undefined,
@@ -89,7 +92,7 @@ function snapshotReportColumns(
 ): ExportColumn<ReportRow>[] {
   const columns: ExportColumn<ReportRow>[] = [{ header: GROUP_LABELS[group], get: (r) => r.key }];
   if (split) {
-    const splitKeys = Array.from(new Set(rows.flatMap((r) => r.split?.map((s) => s.key) ?? [])));
+    const splitKeys = sortKeysForDimension(Array.from(new Set(rows.flatMap((r) => r.split?.map((s) => s.key) ?? []))), split);
     for (const key of splitKeys) {
       columns.push({ header: key, get: (r) => Math.round((r.split?.find((s) => s.key === key)?.value ?? 0) * 100) / 100 });
     }