feat: 2026.1.0-alpha.16 – dashboard banner refactor, period auto-activation, text & docs

Dashboard (dashboard/src/dashboard.tsx, settings.tsx, apiAcademicPeriods.ts):
- Refactor loadHolidayStatus to useCallback with stable empty-deps reference;
  removes location.pathname dependency that caused overlapping API calls at mount
  and left the banner unresolved via request-sequence cancellation
- Add key prop derived from severity:text to Syncfusion MessageComponent to force
  remount on state change, fixing stale banner that ignored React prop/children updates
- Correct German transliterated text to proper Umlauts throughout visible UI strings
  (fuer -> für, oe -> ö, ae -> ä etc. across dashboard and settings views)

Backend (server/init_academic_periods.py):
- Refactor to idempotent two-phase flow: seed default periods only when table is
  empty; on every run activate exactly the non-archived period covering date.today()
- Enforces single-active invariant by deactivating all periods before promoting match
- Emits explicit warning when no period covers current date instead of doing nothing

Deployment (docker-compose.prod.yml):
- Add init_academic_periods.py to server startup chain after migrations and defaults;
  eliminates manual post-deploy step to set an active academic period

Release docs:
- program-info.json: bump to 2026.1.0-alpha.16; fix JSON parse error caused by
  typographic curly quotes in the new changelog entry
- TECH-CHANGELOG.md: detailed alpha.16 section with root-cause motivation for both
  dashboard refactoring decisions (unstable callback ref + Syncfusion stale render)
- DEV-CHANGELOG.md: document dashboard refactor, Syncfusion key fix, Umlaut changes,
  and program-info JSON regression and fix
- README.md: add Latest Release Highlights section for alpha.16
- .github/copilot-instructions.md: sync file map, prod bootstrap note, backend and
  frontend pattern additions for academic period init and Syncfusion remount pattern

dashboard/src/apiAcademicPeriods.ts

@@ -19,8 +19,25 @@ export type PeriodUsage = {
   blockers: string[];
 };
 
+function normalizeAcademicPeriod(period: any): AcademicPeriod {
+  return {
+    id: Number(period.id),
+    name: period.name,
+    displayName: period.displayName ?? period.display_name ?? null,
+    startDate: period.startDate ?? period.start_date,
+    endDate: period.endDate ?? period.end_date,
+    periodType: period.periodType ?? period.period_type,
+    isActive: Boolean(period.isActive ?? period.is_active),
+    isArchived: Boolean(period.isArchived ?? period.is_archived),
+    archivedAt: period.archivedAt ?? period.archived_at ?? null,
+    archivedBy: period.archivedBy ?? period.archived_by ?? null,
+    createdAt: period.createdAt ?? period.created_at,
+    updatedAt: period.updatedAt ?? period.updated_at,
+  };
+}
+
 async function api<T>(url: string, init?: RequestInit): Promise<T> {
-  const res = await fetch(url, { credentials: 'include', ...init });
+  const res = await fetch(url, { credentials: 'include', cache: 'no-store', ...init });
   if (!res.ok) {
     const text = await res.text();
     try {
@@ -35,10 +52,10 @@ async function api<T>(url: string, init?: RequestInit): Promise<T> {
 
 export async function getAcademicPeriodForDate(date: Date): Promise<AcademicPeriod | null> {
   const iso = date.toISOString().slice(0, 10);
-  const { period } = await api<{ period: AcademicPeriod | null }>(
+  const { period } = await api<{ period: any | null }>(
     `/api/academic_periods/for_date?date=${iso}`
   );
-  return period ?? null;
+  return period ? normalizeAcademicPeriod(period) : null;
 }
 
 export async function listAcademicPeriods(options?: {
@@ -53,20 +70,20 @@ export async function listAcademicPeriods(options?: {
     params.set('archivedOnly', '1');
   }
   const query = params.toString();
-  const { periods } = await api<{ periods: AcademicPeriod[] }>(
+  const { periods } = await api<{ periods: any[] }>(
     `/api/academic_periods${query ? `?${query}` : ''}`
   );
-  return Array.isArray(periods) ? periods : [];
+  return Array.isArray(periods) ? periods.map(normalizeAcademicPeriod) : [];
 }
 
 export async function getAcademicPeriod(id: number): Promise<AcademicPeriod> {
-  const { period } = await api<{ period: AcademicPeriod }>(`/api/academic_periods/${id}`);
-  return period;
+  const { period } = await api<{ period: any }>(`/api/academic_periods/${id}`);
+  return normalizeAcademicPeriod(period);
 }
 
 export async function getActiveAcademicPeriod(): Promise<AcademicPeriod | null> {
-  const { period } = await api<{ period: AcademicPeriod | null }>(`/api/academic_periods/active`);
-  return period ?? null;
+  const { period } = await api<{ period: any | null }>(`/api/academic_periods/active`);
+  return period ? normalizeAcademicPeriod(period) : null;
 }
 
 export async function createAcademicPeriod(payload: {
@@ -76,12 +93,12 @@ export async function createAcademicPeriod(payload: {
   endDate: string;
   periodType: 'schuljahr' | 'semester' | 'trimester';
 }): Promise<AcademicPeriod> {
-  const { period } = await api<{ period: AcademicPeriod }>(`/api/academic_periods`, {
+  const { period } = await api<{ period: any }>(`/api/academic_periods`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
     body: JSON.stringify(payload),
   });
-  return period;
+  return normalizeAcademicPeriod(period);
 }
 
 export async function updateAcademicPeriod(
@@ -94,36 +111,36 @@ export async function updateAcademicPeriod(
     periodType: 'schuljahr' | 'semester' | 'trimester';
   }>
 ): Promise<AcademicPeriod> {
-  const { period } = await api<{ period: AcademicPeriod }>(`/api/academic_periods/${id}`, {
+  const { period } = await api<{ period: any }>(`/api/academic_periods/${id}`, {
     method: 'PUT',
     headers: { 'Content-Type': 'application/json' },
     body: JSON.stringify(payload),
   });
-  return period;
+  return normalizeAcademicPeriod(period);
 }
 
 export async function setActiveAcademicPeriod(id: number): Promise<AcademicPeriod> {
-  const { period } = await api<{ period: AcademicPeriod }>(`/api/academic_periods/${id}/activate`, {
+  const { period } = await api<{ period: any }>(`/api/academic_periods/${id}/activate`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
   });
-  return period;
+  return normalizeAcademicPeriod(period);
 }
 
 export async function archiveAcademicPeriod(id: number): Promise<AcademicPeriod> {
-  const { period } = await api<{ period: AcademicPeriod }>(`/api/academic_periods/${id}/archive`, {
+  const { period } = await api<{ period: any }>(`/api/academic_periods/${id}/archive`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
   });
-  return period;
+  return normalizeAcademicPeriod(period);
 }
 
 export async function restoreAcademicPeriod(id: number): Promise<AcademicPeriod> {
-  const { period } = await api<{ period: AcademicPeriod }>(`/api/academic_periods/${id}/restore`, {
+  const { period } = await api<{ period: any }>(`/api/academic_periods/${id}/restore`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
   });
-  return period;
+  return normalizeAcademicPeriod(period);
 }
 
 export async function getAcademicPeriodUsage(id: number): Promise<PeriodUsage> {