feat: init sproutclaw-web — Go+Gin backend + React frontend

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

backend/internal/utils/paths.go

@@ -0,0 +1,25 @@
+package utils
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+// IsPathInsideRoot returns true if candidate is inside (or equal to) root.
+// Both paths are cleaned and compared case-insensitively on Windows.
+func IsPathInsideRoot(root, candidate string) bool {
+	root = filepath.Clean(root)
+	candidate = filepath.Clean(candidate)
+	// normalize separators
+	root = filepath.ToSlash(root)
+	candidate = filepath.ToSlash(candidate)
+	// case-insensitive on Windows
+	rootLow := strings.ToLower(root)
+	candLow := strings.ToLower(candidate)
+	return candLow == rootLow || strings.HasPrefix(candLow, rootLow+"/")
+}
+
+// IsSameResolvedPath compares two paths after cleaning.
+func IsSameResolvedPath(a, b string) bool {
+	return filepath.Clean(a) == filepath.Clean(b)
+}