Add Homebrew cask auto-update on release

.github/workflows/build-release.yml

@@ -159,3 +159,46 @@ jobs:
           name: PostAI-Linux-x64
           path: release/*.AppImage
           retention-days: 7
+
+  # ============================================
+  # Update Homebrew cask on release
+  # ============================================
+  update-homebrew-cask:
+    runs-on: ubuntu-latest
+    needs: [build-electron-mac]
+    if: github.event_name == 'release'
+    steps:
+      - name: Extract version from tag
+        id: version
+        run: echo "version=${GITHUB_REF_NAME#v}" >> "$GITHUB_OUTPUT"
+
+      - name: Download DMG from release
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          gh release download "${{ github.event.release.tag_name }}" \
+            --repo "${{ github.repository }}" \
+            --pattern "PostAI-*-arm64.dmg" \
+            --dir .
+
+      - name: Compute SHA256
+        id: sha
+        run: |
+          SHA=$(shasum -a 256 PostAI-*-arm64.dmg | awk '{print $1}')
+          echo "sha256=${SHA}" >> "$GITHUB_OUTPUT"
+
+      - name: Dispatch update to homebrew-tap
+        env:
+          TAP_GITHUB_TOKEN: ${{ secrets.TAP_GITHUB_TOKEN }}
+        run: |
+          curl -X POST \
+            -H "Accept: application/vnd.github+json" \
+            -H "Authorization: token ${TAP_GITHUB_TOKEN}" \
+            https://api.github.com/repos/Softorize/homebrew-tap/dispatches \
+            -d '{
+              "event_type": "update-postai",
+              "client_payload": {
+                "version": "${{ steps.version.outputs.version }}",
+                "sha256": "${{ steps.sha.outputs.sha256 }}"
+              }
+            }'