Initial commit: EifelDC - Discord-like Matrix chat platform

Includes server (Rust/Axum API proxy with voice management),
Tauri desktop client with Svelte UI, bot-sdk, Docker infra
(Synapse, PostgreSQL, Coturn, Nginx), and CI/CD pipeline.

infra/nginx/eifeldc.conf

@@ -0,0 +1,79 @@
+upstream eifeldc_server {
+    server eifeldc:3000;
+}
+
+upstream synapse_server {
+    server synapse:8008;
+}
+
+server {
+    listen 80;
+    server_name eifeldc.local;
+    return 301 https://$host$request_uri;
+}
+
+server {
+    listen 443 ssl http2;
+    server_name eifeldc.local;
+
+    ssl_certificate /etc/letsencrypt/live/eifeldc.local/fullchain.pem;
+    ssl_certificate_key /etc/letsencrypt/live/eifeldc.local/privkey.pem;
+    ssl_protocols TLSv1.2 TLSv1.3;
+    ssl_ciphers HIGH:!aNULL:!MD5;
+    ssl_prefer_server_ciphers on;
+    ssl_session_cache shared:SSL:10m;
+    ssl_session_timeout 10m;
+
+    client_max_body_size 50M;
+
+    add_header X-Frame-Options SAMEORIGIN;
+    add_header X-Content-Type-Options nosniff;
+    add_header X-XSS-Protection "1; mode=block";
+    add_header Referrer-Policy strict-origin-when-cross-origin;
+
+    location /.well-known/matrix/server {
+        default_type application/json;
+        return 200 '{"m.server": "eifeldc.local:443"}';
+    }
+
+    location /.well-known/matrix/client {
+        default_type application/json;
+        return 200 '{"m.homeserver": {"base_url": "https://eifeldc.local"}}';
+    }
+
+    location ~ ^/_matrix/(client|media|federation|key|v2) {
+        proxy_pass http://synapse_server;
+        proxy_set_header Host $host;
+        proxy_set_header X-Forwarded-For $remote_addr;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_http_version 1.1;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection "upgrade";
+        proxy_read_timeout 600s;
+        proxy_send_timeout 600s;
+    }
+
+    location /_synapse {
+        proxy_pass http://synapse_server;
+        proxy_set_header Host $host;
+        proxy_set_header X-Forwarded-For $remote_addr;
+        proxy_set_header X-Forwarded-Proto $scheme;
+    }
+
+    location /api/ {
+        proxy_pass http://eifeldc_server;
+        proxy_set_header Host $host;
+        proxy_set_header X-Forwarded-For $remote_addr;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_http_version 1.1;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection "upgrade";
+    }
+
+    location / {
+        proxy_pass http://eifeldc_server;
+        proxy_set_header Host $host;
+        proxy_set_header X-Forwarded-For $remote_addr;
+        proxy_set_header X-Forwarded-Proto $scheme;
+    }
+}