feat: add Portainer deployment via Docker Compose on port 4422

Multi-stage Dockerfile: node:22.13.1-alpine3.21 builds the Vite
bundle, nginx:1.27.4-alpine3.21-slim serves dist/ on container :80.
Compose maps host :4422 to container :80 with a wget healthcheck
and unless-stopped restart policy.

nginx.conf serves Vite's content-addressed /assets/ as immutable,
caches images for 30d, falls back to index.html for SPA routes,
and sets X-Frame-Options / X-Content-Type-Options / Referrer-Policy
/ Permissions-Policy headers. Server tokens off.

.dockerignore keeps the build context lean (no node_modules, dist,
.git, archive, or compose files).

Pin to image digests in Portainer's stack editor for full lock.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,16 @@
+services:
+  kammergut:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    image: kammergut:0.1.0
+    container_name: kammergut
+    restart: unless-stopped
+    ports:
+      - "4422:80"
+    healthcheck:
+      test: ["CMD", "wget", "-q", "--spider", "http://127.0.0.1/"]
+      interval: 30s
+      timeout: 3s
+      retries: 3
+      start_period: 5s