feat: GPU offload, signup limit, load tests & capacity planning

- Route all AI workloads (Ollama, STT, TTS, Image Gen) to GPU server
  (192.168.178.11) via LAN instead of host.docker.internal
- Upgrade default model to gemma3:12b and max concurrent to 5
- Add daily signup limit service (MAX_DAILY_SIGNUPS env var)
- Add GET /api/v1/auth/signup-status public endpoint
- Add k6 load test suite (web-apps, auth, sync-websocket, ollama)
- Add capacity planning documentation
- Fix: add eslint-config to sveltekit-base and calendar Dockerfiles

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

load-tests/README.md

@@ -0,0 +1,58 @@
+# Load Tests
+
+k6-basierte Load Tests fuer die Mana-Infrastruktur.
+
+## Setup
+
+```bash
+# k6 installieren (macOS)
+brew install k6
+
+# WebSocket-Extension (fuer Sync-Tests)
+# k6 hat WebSocket-Support eingebaut
+```
+
+## Tests ausfuehren
+
+```bash
+# Gegen lokale Umgebung
+k6 run load-tests/web-apps.js
+k6 run load-tests/auth-api.js
+k6 run load-tests/sync-websocket.js
+k6 run load-tests/llm-ollama.js
+
+# Gegen Produktion (vorsichtig!)
+k6 run -e BASE_URL=https://mana.how load-tests/web-apps.js
+
+# Mit mehr/weniger Last
+k6 run --vus 100 --duration 5m load-tests/web-apps.js
+
+# JSON-Output fuer Grafana
+k6 run --out json=results.json load-tests/web-apps.js
+```
+
+## Test-Szenarien
+
+| Script | Ziel | Default VUs | Dauer |
+|--------|------|-------------|-------|
+| `web-apps.js` | SvelteKit Frontends (HTML-Responses) | 10→50→10 | 5 min |
+| `auth-api.js` | Login, Register, Token Validation | 5→20→5 | 4 min |
+| `sync-websocket.js` | mana-sync WebSocket Connections | 10→30→10 | 5 min |
+| `llm-ollama.js` | Ollama Chat Completions | 1→3→1 | 3 min |
+
+## Metriken interpretieren
+
+| Metrik | Gut | Akzeptabel | Schlecht |
+|--------|-----|-----------|---------|
+| http_req_duration (p95) | < 200ms | < 1s | > 2s |
+| http_req_failed | 0% | < 1% | > 5% |
+| ws_connecting (p95) | < 100ms | < 500ms | > 1s |
+| iterations | Steigend | Stabil | Fallend |
+
+## Monitoring waehrend Tests
+
+Grafana-Dashboard auf http://localhost:8080 (oder https://grafana.mana.how) beobachten:
+- Container CPU/RAM (cAdvisor)
+- PostgreSQL Connections
+- Redis Commands/sec
+- Netzwerk-Throughput