ci: only release tip releases when triggered from the main branch

.github/workflows/release-tip.yml

@@ -372,6 +372,10 @@ jobs:
 
       # Create our appcast for Sparkle
       - name: Generate Appcast
+        if: |
+          github.event.workflow_run.conclusion == 'success' &&
+          github.repository_owner == 'ghostty-org' &&
+          github.ref_name == 'main'
         env:
           SPARKLE_KEY: ${{ secrets.PROD_MACOS_SPARKLE_KEY }}
         run: |
@@ -403,12 +407,20 @@ jobs:
       # Now upload our appcast. This ensures that the appcast never
       # gets out of sync with the binaries.
       - name: Prep R2 Storage for Appcast
+        if: |
+          github.event.workflow_run.conclusion == 'success' &&
+          github.repository_owner == 'ghostty-org' &&
+          github.ref_name == 'main'
         run: |
           rm -r blob
           mkdir blob
           cp appcast_new.xml blob/appcast.xml
 
       - name: Upload Appcast to R2
+        if: |
+          github.event.workflow_run.conclusion == 'success' &&
+          github.repository_owner == 'ghostty-org' &&
+          github.ref_name == 'main'
         uses: ryand56/r2-upload-action@b801a390acbdeb034c5e684ff5e1361c06639e7c # v1.4
         with:
           r2-account-id: ${{ secrets.CF_R2_TIP_ACCOUNT_ID }}