feat: voice-agent MVP — LXC web frontend + Mac AI worker

LXC-Frontend (FastAPI + HTML/JS):
- Audio-Upload (MP3/WAV/M4A/MP4/OGG/FLAC, max. 500 MB)
- SQLite Job-Store, BackgroundTask-Pipeline
- Job-Liste mit Live-Status, Downloads (DOCX + JSON)
- Mac-Health-Indicator im UI

Mac-Worker (FastAPI):
- /api/transcribe (lightning-whisper-mlx | faster-whisper | mock)
- /api/summarize + /api/protocol via Ollama (llama3.1:8b)
- /api/export/docx via python-docx

Deploy:
- systemd-Service, Nginx Reverse-Proxy
- deploy/install.sh: idempotentes LXC-Setup

Doku: README.md, lxc-frontend/README.md, mac-worker/README.md

deploy/nginx/voice-agent.conf

@@ -0,0 +1,20 @@
+server {
+    listen 80 default_server;
+    server_name _;
+
+    # Upload-Limit muss zu MAX_UPLOAD_MB in .env passen
+    client_max_body_size 600M;
+
+    # Lange Verarbeitung — Timeouts hoch
+    proxy_read_timeout 1800;
+    proxy_send_timeout 1800;
+
+    location / {
+        proxy_pass http://127.0.0.1:8000;
+        proxy_http_version 1.1;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+    }
+}