chore(build): use golang:1.26-alpine container instead of ubuntu-latest

Switch from the full ubuntu runner image to golang:1.26-alpine via the
container: directive. Go is pre-installed so actions/setup-go is dropped;
curl, git, and jq are added with apk in the first step.

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

.gitea/workflows/release.yml

@@ -0,0 +1,62 @@
+name: release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  release:
+    name: Build and publish release
+    runs-on: ubuntu-latest
+    container:
+      image: golang:1.26-alpine
+
+    steps:
+      - name: Install tools
+        run: apk add --no-cache curl git jq
+
+      - uses: actions/checkout@v4
+
+      - name: Build Linux (amd64)
+        env:
+          GOOS: linux
+          GOARCH: amd64
+          CGO_ENABLED: "0"
+        run: |
+          go build -trimpath -ldflags="-s -w" \
+            -o glint-${{ github.ref_name }}-linux-amd64 \
+            ./cmd/glint/...
+
+      - name: Build Windows (amd64)
+        env:
+          GOOS: windows
+          GOARCH: amd64
+          CGO_ENABLED: "0"
+        run: |
+          go build -trimpath -ldflags="-s -w" \
+            -o glint-${{ github.ref_name }}.exe \
+            ./cmd/glint/...
+
+      - name: Create release and upload assets
+        env:
+          TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TAG: ${{ github.ref_name }}
+          API_URL: ${{ github.api_url }}
+          REPO: ${{ github.repository }}
+        run: |
+          release_id=$(curl -sf -X POST \
+            -H "Authorization: token $TOKEN" \
+            -H "Content-Type: application/json" \
+            "$API_URL/repos/$REPO/releases" \
+            -d "{\"tag_name\":\"$TAG\",\"name\":\"$TAG\",\"draft\":false,\"prerelease\":false}" \
+            | jq -r .id)
+
+          for file in glint-${{ github.ref_name }}-linux-amd64 glint-${{ github.ref_name }}.exe; do
+            curl -sf -X POST \
+              -H "Authorization: token $TOKEN" \
+              -H "Content-Type: application/octet-stream" \
+              "$API_URL/repos/$REPO/releases/$release_id/assets?name=$file" \
+              --data-binary "@$file"
+            echo "uploaded: $file"
+          done