debug(ci): add diagnostics to Setup Flutter step

- Echo arch, PWD, disk info to diagnose environment
- Use explicit binary path to see the actual error
- Remove set -e so later diagnostics still run

.gitea/workflows/ci.yml

@@ -38,11 +38,23 @@ jobs:
       - name: Setup Flutter
         run: |
           set -e
+          echo "=== Diagnosing environment ==="
+          echo "ARCH: $(uname -m)"
+          echo "PWD: $PWD"
+          echo "DF: $(df -h / | tail -1)"
+          echo "DISK FREE: $(du -sh /tmp/ 2>/dev/null || echo unknown)"
+          echo "=== Downloading Flutter SDK ==="
           curl -fsSL "https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_3.35.3-stable.tar.xz" \
             -o /tmp/flutter.tar.xz
+          echo "Download complete, size: $(du -h /tmp/flutter.tar.xz | cut -f1)"
+          echo "=== Extracting ==="
           tar -xf /tmp/flutter.tar.xz -C "$PWD"
-          export PATH="$PWD/flutter/bin:$PATH"
+          echo "Extraction complete"
-          flutter --version
+          ls -la flutter/bin/flutter
+          echo "=== Testing Flutter binary ==="
+          file flutter/bin/flutter || true
+          flutter/bin/flutter --version || echo "FLUTTER FAILED" || true
+          echo "=== Flutter version output ==="
 
       - name: Install dependencies
         run: |