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.

tests/unit/security.test.ts

@@ -1,6 +1,14 @@
 import { NextRequest } from "next/server";
 import { afterEach, describe, expect, it, vi } from "vitest";
-import { sanitizeForSpreadsheetCell, toCsv } from "@/lib/export";
+import { exportFilename, sanitizeForSpreadsheetCell, toCsv } from "@/lib/export";
+import {
+  parseEventDateParam,
+  parseEventType,
+  parseGroupDimension,
+  parseIsoDateParam,
+  parseMeasure,
+  parseSplitDimension,
+} from "@/lib/reports";
 import { sanitizeIlikeTerm } from "@/lib/supabase/query";
 
 // The route under test imports lib/supabase/admin.ts, which is guarded by
@@ -44,6 +52,60 @@ describe("sanitizeIlikeTerm", () => {
   });
 });
 
+describe("report query-string parsing", () => {
+  it("falls back to a known dimension instead of passing an unknown one through", () => {
+    expect(parseMeasure("bogus")).toBe("headcount");
+    expect(parseGroupDimension("bogus")).toBe("division");
+    expect(parseMeasure("fte")).toBe("fte");
+    expect(parseGroupDimension("weekday")).toBe("weekday");
+  });
+
+  it("treats an unknown split or event type as 'none' rather than a value", () => {
+    expect(parseSplitDimension("bogus")).toBeNull();
+    expect(parseSplitDimension("")).toBeNull();
+    expect(parseSplitDimension("location")).toBe("location");
+    expect(parseEventType("bogus")).toBeNull();
+    expect(parseEventType("Eintritt")).toBe("Eintritt");
+  });
+
+  // Object.hasOwn, not `in`: a plain `value in LABELS` check would accept
+  // "constructor" or "toString" off the prototype chain as a valid dimension.
+  it("does not accept inherited Object properties as dimensions", () => {
+    expect(parseGroupDimension("constructor")).toBe("division");
+    expect(parseSplitDimension("toString")).toBeNull();
+    expect(parseEventType("hasOwnProperty")).toBeNull();
+  });
+
+  it("rejects a Stichtag that is not a real calendar date", () => {
+    expect(parseIsoDateParam("2026-03-05")).toBe("2026-03-05");
+    expect(parseIsoDateParam("2026-02-30")).toBeUndefined();
+    expect(parseIsoDateParam("heute")).toBeUndefined();
+    expect(parseIsoDateParam('2026-03-05"; rm -rf /')).toBeUndefined();
+  });
+
+  it("keeps the open-interval sentinel but still rejects free text", () => {
+    expect(parseEventDateParam("open")).toBe("open");
+    expect(parseEventDateParam("2026-01-01")).toBe("2026-01-01");
+    expect(parseEventDateParam("whenever")).toBeUndefined();
+  });
+});
+
+describe("exportFilename", () => {
+  // The base is assembled from query-string values and lands in a
+  // Content-Disposition header, so a quote in it would otherwise break out
+  // of the quoted filename.
+  it("strips characters that would escape the Content-Disposition filename", () => {
+    const name = exportFilename('bericht"; attachment; filename="evil', "csv");
+    expect(name).not.toContain('"');
+    expect(name).not.toContain(";");
+    expect(name.endsWith(".csv")).toBe(true);
+  });
+
+  it("keeps an ordinary base readable", () => {
+    expect(exportFilename("bericht-headcount-division", "xlsx")).toMatch(/^bericht-headcount-division-\d{4}-\d{2}-\d{2}\.xlsx$/);
+  });
+});
+
 describe("cron auth guard (/api/cron/apply-pending-changes)", () => {
   afterEach(() => {
     vi.unstubAllEnvs();