fix(smoke-test): add Docker file sharing permission check for macOS

Add pre-flight check to detect Docker Desktop file sharing issues:

- After creating data directories, verify Docker can access them
- If access fails, print helpful error message with fix instructions
- Directs users to Docker Desktop Settings -> Resources -> File sharing

Prevents confusing 'operation not permitted' errors during smoke tests.

scripts/dev/smoke-test.sh

@@ -115,6 +115,19 @@ if [ "$env" = "dev" ]; then
         "$repo_root/data/dev/active" \
         "$repo_root/data/dev/workspaces"
 
+    # Verify Docker can access the data directory (macOS file sharing check)
+    if ! docker run --rm -v "$repo_root/data/dev:/test-data:ro" alpine:3.19 ls /test-data >/dev/null 2>&1; then
+        echo "ERROR: Docker cannot access $repo_root/data/dev"
+        echo ""
+        echo "This is a Docker Desktop file sharing issue. To fix:"
+        echo "1. Open Docker Desktop -> Settings -> Resources -> File sharing"
+        echo "2. Add or verify: $repo_root"
+        echo "3. Click 'Apply & Restart'"
+        echo ""
+        echo "Alternatively, run: mkdir -p $repo_root/data/dev/{redis,minio,prometheus,grafana,loki,logs,experiments,active,workspaces}"
+        exit 1
+    fi
+
     stack_name="dev"
     api_wait_seconds=180
     prometheus_wait_seconds=180