feat(quality): Sprint 2 pre-deploy gates and server smoke tests

Extract Express app factory for testability, add Vitest/Supertest API
smoke tests, root npm run check script, and deployment docs. Fix
express-rate-limit IPv6 keyGenerator for feedback limiter.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/deployment/predeploy.md

@@ -0,0 +1,38 @@
+# Pre-Deploy-Checks (ohne CI)
+
+Vor jedem Update auf **https://kapteins-daagbok.eu/** lokal ausführen:
+
+```bash
+npm run check
+```
+
+Das Skript [`scripts/predeploy-check.sh`](../../scripts/predeploy-check.sh) führt aus:
+
+1. i18n-Key-Validierung (`validate:i18n`)
+2. Client: `test` → `build` (TypeScript via `tsc -b`)
+3. Server: `test` → `build`
+
+## Einzelbefehle (Repo-Root)
+
+| Befehl | Inhalt |
+|--------|--------|
+| `npm run lint` | ESLint (Client) — optional, noch nicht Teil von `check` |
+| `npm run test` | Vitest Client + Server |
+| `npm run build` | Production-Build beider Pakete |
+| `npm run predeploy` | Alias für `npm run check` |
+
+## Server-Tests
+
+Smoke-Tests in `server/src/api.smoke.test.ts` — keine echte Datenbank (Prisma gemockt). Prüfen u. a. Health, 401 ohne Session, öffentliche Collaboration-Validierung.
+
+```bash
+cd server && npm test
+```
+
+## Nach erfolgreichem Check
+
+```bash
+./scripts/update-prod.sh
+```
+
+Oder manuell auf dem Server: `git pull`, `docker compose build`, `docker compose up -d` (siehe [npm-security.md](npm-security.md)).