fix: IsHiddenPath returns false for "." and "/" (current dir/root are not hidden)

path.Clean(".") returns "." which starts with a dot, causing IsHiddenPath
to incorrectly treat the current directory as hidden. Add explicit checks
for "." and "/" before the dot-prefix check.

Fixed in both mfer/scanner.go and internal/scanner/scanner.go.

mfer/scanner_test.go

@@ -352,6 +352,8 @@ func TestIsHiddenPath(t *testing.T) {
 		{"/absolute/.hidden", true},
 		{"./relative", false}, // path.Clean removes leading ./
 		{"a/b/c/.d/e", true},
+		{".", false},          // current directory is not hidden
+		{"/", false},          // root is not hidden
 	}
 
 	for _, tt := range tests {