fix: CI checkout cd to home before cleanup to avoid cwd error

The runner cwd is the workspace itself, so deleting it removes the
shell's cwd. cd to home first, then clean workspace before clone.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build-iso.yml

@@ -12,13 +12,13 @@ jobs:
     steps:
       - name: Checkout
         run: |
-          WORKSPACE="${GITHUB_WORKSPACE:-$(pwd)}"
+          cd /home/archipelago
+          WORKSPACE="${GITHUB_WORKSPACE}"
           CLONE_URL="${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY}.git"
-          # Inject token for private repo auth
           if [ -n "$GITHUB_TOKEN" ]; then
             CLONE_URL=$(echo "$CLONE_URL" | sed "s|https://|https://token:${GITHUB_TOKEN}@|")
           fi
-          rm -rf "$WORKSPACE"
+          [ -d "$WORKSPACE" ] && find "$WORKSPACE" -mindepth 1 -delete
           git clone --depth 1 --branch "${GITHUB_REF_NAME:-main}" "$CLONE_URL" "$WORKSPACE"
           cd "$WORKSPACE"
           echo "Checked out $(git rev-parse --short HEAD) on ${GITHUB_REF_NAME:-main}"