feat: support tag-based releases

- Trigger on both push to main and v* tags
- Use tag name for version when pushing tags (e.g., v2.0.0)
- Auto-generate version for branch pushes
- Tag releases are stable, branch releases are prerelease

.github/workflows/release.yml

@@ -3,6 +3,8 @@ name: Build & Release
 on:
   push:
     branches: ["main"]
+    tags:
+      - "v*"
 
 permissions:
   contents: write
@@ -60,7 +62,11 @@ jobs:
       - name: Generate version from commit
         id: version
         run: |
-          VERSION="v$(date +%Y.%m.%d)-$(git rev-parse --short HEAD)"
+          if [[ $GITHUB_REF == refs/tags/v* ]]; then
+            VERSION="${GITHUB_REF#refs/tags/}"
+          else
+            VERSION="v$(date +%Y.%m.%d)-$(git rev-parse --short HEAD)"
+          fi
           echo "version=$VERSION" >> $GITHUB_OUTPUT
           echo "Generated version: $VERSION"
 
@@ -96,4 +102,4 @@ jobs:
           files: artifacts/*
           generate_release_notes: true
           draft: false
-          prerelease: true
+          prerelease: ${{ startsWith(github.ref, 'refs/tags/') && false || true }}