ci: trigger build on version tag push with auto-release

Changed workflow to:
- Trigger on push of v* tags instead of release publish
- Auto-create Gitea release via API
- Then build and push Docker image

This simplifies deployment: just push a version tag.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitea/workflows/build.yml

@@ -1,12 +1,25 @@
 name: Build and Push
 
 on:
-  release:
-    types: [published]
+  push:
+    tags:
+      - 'v*'
 
 jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Create Gitea Release
+        run: |
+          curl -sf -X POST \
+            -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
+            -H "Content-Type: application/json" \
+            -d '{"tag_name": "${{ github.ref_name }}", "name": "Release ${{ github.ref_name }}", "body": "Automated release for ${{ github.ref_name }}"}' \
+            "${{ github.server_url }}/api/v1/repos/${{ github.repository }}/releases"
+
   build:
     runs-on: ubuntu-latest
+    needs: release
     steps:
       - uses: actions/checkout@v4