Add install script, CI workflows, and release pipeline

- Install script: curl-pipe-sh installer that downloads the right
  binary for the user's OS/arch from GitHub Releases
- CI workflow: runs go vet + go test for both Go modules and builds
  the web app on push/PR
- Release workflow: goreleaser builds cross-platform binaries
  (linux/darwin, amd64/arm64) on version tags
- Node-agent defaults BETTERNAS_CONTROL_PLANE_URL to
  https://api.betternas.com so users only need username/password

.github/workflows/ci.yaml

@@ -0,0 +1,47 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  test-control-plane:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: apps/control-plane/go.mod
+          cache-dependency-path: apps/control-plane/go.sum
+      - run: go vet ./...
+        working-directory: apps/control-plane
+      - run: go test -count=1 ./...
+        working-directory: apps/control-plane
+
+  test-node-agent:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: apps/node-agent/go.mod
+          cache-dependency-path: apps/node-agent/go.sum
+      - run: go vet ./...
+        working-directory: apps/node-agent
+      - run: go test -count=1 ./...
+        working-directory: apps/node-agent
+
+  build-web:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm --filter @betternas/web build
+        env:
+          NEXT_PUBLIC_BETTERNAS_API_URL: https://api.betternas.com

.github/workflows/release.yaml

@@ -0,0 +1,27 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - "v*"
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: apps/node-agent/go.mod
+          cache-dependency-path: apps/node-agent/go.sum
+      - uses: goreleaser/goreleaser-action@v6
+        with:
+          version: latest
+          args: release --clean
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}