041 expression backslash escape

// Test 210_041: Expression Backslash Escape
// Tests that strings with escaped backslashes parse correctly.
// "path\\to\\file" should NOT be flagged as Zig code (\\t ≠ \t).

const std = @import("std");

~event process_path { path: []const u8 }
| done { result: []const u8 }

~proc process_path {
    std.debug.print("Processing path: {s}\n", .{path});
    return .{ .done = .{ .result = path } };
}

// This should parse correctly:
// - "path\\to\\file" contains \\t (escaped backslash + t)
// - NOT \t (tab escape sequence)
// Previously failed with "Zig code not allowed in flows"
~process_path(path: "path\\to\\file")
| done _ |> _