032 implicit source param

// Test 618: Explicit Source Parameter
// First validate that explicit source: { } syntax works
// TODO: Test implicit syntax after this works
// Validates that Source parameters work like Source with implicit parameter name

~import std/io

~[comptime|transform]event capture.source {
    source: Source,
    item: *const Item
}
| transformed Item

~proc capture.source|zig {
    // For MVP: Just return the item unchanged to prove transform machinery works
    // TODO: Actually transform the source into inline code
    return .{ .transformed = item.* };
}

// Use explicit source parameter
// The transform replaces this entire flow with a new AST node
~capture.source {
    const x = 42;
    const y = x + 1;
}
| transformed _ |> _