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

.github/workflows/ci.yml

@@ -0,0 +1,99 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  rust:
+    name: Rust (fmt, clippy, tests)
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v5
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+      - uses: Swatinem/rust-cache@v2
+      - name: Install Tauri system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libwebkit2gtk-4.1-dev libayatana-appindicator3-dev librsvg2-dev
+      - name: Placeholder launcher frontend (tauri::generate_context needs it)
+        run: mkdir -p launcher/dist && echo '<!doctype html>' > launcher/dist/index.html
+      - run: cargo fmt --all --check
+      - run: cargo clippy --workspace --all-targets --locked -- -D warnings
+      - run: cargo test --workspace --locked
+
+  web:
+    name: Web UIs (type-check + build)
+    runs-on: ubuntu-24.04
+    strategy:
+      matrix:
+        app: [panel/web, launcher]
+    defaults:
+      run:
+        working-directory: ${{ matrix.app }}
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-node@v5
+        with:
+          node-version: 22
+          cache: npm
+          cache-dependency-path: ${{ matrix.app }}/package-lock.json
+      - run: npm ci --no-audit --no-fund
+      - run: npm run check
+      - run: npm run build
+
+  launcher-windows:
+    name: Launcher (Windows build check)
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+      - uses: actions/setup-node@v5
+        with:
+          node-version: 22
+          cache: npm
+          cache-dependency-path: launcher/package-lock.json
+      - run: npm ci --no-audit --no-fund
+        working-directory: launcher
+      - run: npm run build
+        working-directory: launcher
+      - run: cargo clippy -p scopenet-launcher --locked -- -D warnings
+      - run: cargo test -p scopenet-launcher -p scopenet-core -p scopenet-shared --locked
+
+  engine-online:
+    name: Real installs (Mojang, Fabric, Quilt, Forge, NeoForge)
+    runs-on: ubuntu-24.04
+    # Talks to third-party servers; a hiccup there shouldn't block merges.
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v5
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+      - name: Install games (vanilla, legacy, Fabric, Quilt, Forge, NeoForge)
+        run: cargo test -p scopenet-core --test online --locked -- --ignored --test-threads=2 --nocapture
+
+  docker:
+    name: Docker image builds
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v5
+      - uses: docker/setup-buildx-action@v3
+      - uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: false
+          cache-from: type=gha
+          cache-to: type=gha,mode=max