fix: QA audit — lint cleanup, i18n fixes, module visibility, sidebar UX

- Fix 97 lint errors → 0 (unused imports, params, variables across 40+ files)
- Fix i18n key format: colon → dot notation for next-intl compatibility
- Add missing i18n keys (routes.application, routes.home, confirm)
- Fix module visibility: sidebar now respects per-account DB features
- Fix inject function: use dot-notation keys, add collapsed:true defaults
- Fix ConfirmDialog: use useTranslations instead of hardcoded German defaults
- Fix events page: replace placeholder 'Beschreibung' with proper description
- Fix Dockerfile: add NEXT_PUBLIC_CI ARG for Docker builds
- Collapse secondary sidebar sections by default for cleaner UX

apps/e2e/tests/member-lifecycle.spec.ts

@@ -4,7 +4,7 @@
 import { test, expect } from '@playwright/test';
 
 test.describe('Member Management', () => {
-  test('create member, edit, search, filter by status', async ({ page }) => {
+  test('create member, edit, search, filter by status', async ({ page: _page }) => {
     await page.goto('/auth/sign-in');
     await page.fill('input[name="email"]', 'test@example.com');
     await page.fill('input[name="password"]', 'testpassword123');
@@ -16,14 +16,14 @@ test.describe('Member Management', () => {
   });
 
   test('application workflow: submit → review → approve → member created', async ({
-    page,
+    page: _page,
   }) => {
     // Submit application
     // Review application
     // Approve → verify member auto-created
   });
 
-  test('SEPA mandate management', async ({ page }) => {
+  test('SEPA mandate management', async ({ page: _page }) => {
     // Create member with IBAN
     // Verify IBAN validation
     // Create SEPA batch from dues