Add dev branch support to build workflow

dev push  → artifact named fabledapp-dev-<sha>
main push → artifact named fabledapp-<sha>
tag push  → artifact + Forgejo Release

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

.forgejo/workflows/build.yml

@@ -1,7 +1,6 @@
-# Runs on pushes to main and on version tags (v*).
-#
-# Branch push (main):  builds APK, uploads as workflow artifact (30 day retention)
-# Tag push (v26.03.09): builds APK, creates a Forgejo Release with APK attached
+# Branch push (dev):    builds APK, uploads as artifact named fabledapp-dev-<sha>
+# Branch push (main):   builds APK, uploads as artifact named fabledapp-<sha>
+# Tag push (v26.03.09): builds APK, uploads artifact + creates Forgejo Release
 #
 # To cut a release:
 #   git tag v26.03.09 && git push origin v26.03.09
@@ -12,7 +11,7 @@ name: Build APK
 
 on:
   push:
-    branches: [main]
+    branches: [main, dev]
     tags: ["v*"]
     paths:
       - "lib/**"
@@ -37,10 +36,19 @@ jobs:
       - name: Build release APK
         run: flutter build apk --release
 
+      - name: Set artifact name
+        id: artifact
+        run: |
+          if [[ "${{ github.ref }}" == "refs/heads/dev" ]]; then
+            echo "name=fabledapp-dev-${{ github.sha }}" >> $GITHUB_OUTPUT
+          else
+            echo "name=fabledapp-${{ github.sha }}" >> $GITHUB_OUTPUT
+          fi
+
       - name: Upload artifact
         uses: actions/upload-artifact@v4
         with:
-          name: fabledapp-${{ github.sha }}
+          name: ${{ steps.artifact.outputs.name }}
           path: build/app/outputs/flutter-apk/app-release.apk
           retention-days: 30