ci: add release pipeline triggered by VERSION file

When VERSION is updated on main, the pipeline builds and pushes the
frontend Docker image to ghcr.io/helmcode/agentcrew-frontend with both
the version tag and :latest. It also creates a git tag and GitHub
Release with auto-generated notes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: barckcode

.github/workflows/release.yml

@@ -0,0 +1,62 @@
+name: Release
+
+on:
+  push:
+    branches: [main]
+    paths: [VERSION]
+
+permissions:
+  contents: write
+  packages: write
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Read version
+        id: version
+        run: echo "version=$(cat VERSION | tr -d '[:space:]')" >> "$GITHUB_OUTPUT"
+
+      - name: Check tag does not exist
+        run: |
+          if git rev-parse "v${{ steps.version.outputs.version }}" >/dev/null 2>&1; then
+            echo "::error::Tag v${{ steps.version.outputs.version }} already exists"
+            exit 1
+          fi
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push frontend image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: true
+          build-args: |
+            VITE_API_URL=
+          tags: |
+            ghcr.io/helmcode/agentcrew-frontend:${{ steps.version.outputs.version }}
+            ghcr.io/helmcode/agentcrew-frontend:latest
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+      - name: Create git tag
+        run: |
+          git tag "v${{ steps.version.outputs.version }}"
+          git push origin "v${{ steps.version.outputs.version }}"
+
+      - name: Create GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          tag_name: v${{ steps.version.outputs.version }}
+          name: v${{ steps.version.outputs.version }}
+          generate_release_notes: true

VERSION

@@ -0,0 +1 @@
+0.1.0