Add Docker image, Compose, CI/CD workflows and docs

- Multi-arch (amd64/arm64) panel image: static musl binary on scratch,
  cross-compiled with cargo-zigbuild (no QEMU), non-root, healthcheck
- docker-compose.yml + .env.example for one-command deployment
- CI: fmt, clippy, tests, web type-checks, Windows launcher build,
  real-network installs of vanilla/Fabric/Quilt/Forge/NeoForge,
  Docker build
- Release: Windows NSIS installer with baked-in panel URL, GHCR image
  push and GitHub release (tag push or manual dispatch)
- README, admin guide, Microsoft auth setup, architecture, development
- rustfmt config and formatting pass

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011ARcGWxLx21FwXJ3yfGriS

docker-compose.yml

@@ -0,0 +1,36 @@
+# ScopeNet admin panel
+#
+#   cp .env.example .env    # set ADMIN_PASSWORD at least
+#   docker compose up -d
+#
+# Then open http://localhost:8080 (or your domain behind a reverse proxy).
+services:
+  panel:
+    image: ghcr.io/scopeddlol/scopenet-mc-panel:latest
+    # Or build from source:  docker compose build
+    build: .
+    container_name: scopenet-panel
+    restart: unless-stopped
+    ports:
+      - "${PANEL_PORT:-8080}:8080"
+    environment:
+      ADMIN_USERNAME: ${ADMIN_USERNAME:-admin}
+      # First start only: creates the admin account. If empty, a random
+      # password is printed in `docker compose logs panel`.
+      ADMIN_PASSWORD: ${ADMIN_PASSWORD:-}
+      # Signs login tokens. Auto-generated into the data volume if empty.
+      JWT_SECRET: ${JWT_SECRET:-}
+      # Optional — can also be set in the panel's Settings page.
+      CURSEFORGE_API_KEY: ${CURSEFORGE_API_KEY:-}
+      MAX_UPLOAD_MB: ${MAX_UPLOAD_MB:-2048}
+      RUST_LOG: ${RUST_LOG:-info}
+    volumes:
+      - panel-data:/data
+    # Very small footprint: the panel idles at ~10 MB RAM.
+    deploy:
+      resources:
+        limits:
+          memory: 256M
+
+volumes:
+  panel-data: