fix: Only build and upload artifacts on main branch

Adds conditions to build and upload jobs to only run when triggered by pushes to the main branch, preventing unnecessary builds on pull requests.

Changes:
- Updated build-web job condition to include `github.ref == 'refs/heads/main'`
- Updated build-release job condition to include `github.ref == 'refs/heads/main'`
- Updated upload-to-release job condition to include `github.ref == 'refs/heads/main'`

This ensures:
- Pull requests only update the draft release notes (via release-drafter)
- Actual builds and artifact uploads only happen on main branch pushes
- More efficient CI/CD pipeline with reduced unnecessary builds

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

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

.github/workflows/draft-release.yml

@@ -30,7 +30,7 @@ jobs:
   build-web:
     name: Build Web App
     needs: draft-release
-    if: needs.draft-release.outputs.tag-name != ''
+    if: needs.draft-release.outputs.tag-name != '' && github.ref == 'refs/heads/main'
     runs-on: ubuntu-latest
 
     steps:
@@ -67,7 +67,7 @@ jobs:
   build-release:
     name: Build Release - ${{ matrix.os }}
     needs: draft-release
-    if: needs.draft-release.outputs.tag-name != ''
+    if: needs.draft-release.outputs.tag-name != '' && github.ref == 'refs/heads/main'
     runs-on: ${{ matrix.os }}
 
     strategy:
@@ -124,7 +124,7 @@ jobs:
   upload-to-release:
     name: Upload to GitHub Release
     needs: [draft-release, build-web, build-release]
-    if: needs.draft-release.outputs.tag-name != ''
+    if: needs.draft-release.outputs.tag-name != '' && github.ref == 'refs/heads/main'
     runs-on: ubuntu-latest
 
     steps: