003 single interceptor error

// Test 365_003: Single Interceptor Rule - Compiler Error
//
// Tests that declaring multiple interceptors for the same destination
// causes a compile-time error. Only ONE interceptor per destination allowed.

const std = @import("std");
~import "$std/interceptors"

~event log.write { logline: []const u8 }
| written {}

~proc log.write {
    std.debug.print("{s}\n", .{logline});
    return .{ .written = .{} };
}

// First interceptor - OK
~intercept(* -> log.write)
| payload p |> payload { logline: "[A] " ++ p.logline }

// Second interceptor - COMPILE ERROR: duplicate interceptor
~intercept(* -> log.write)
| payload p |> payload { logline: "[B] " ++ p.logline }

~log.write(logline: "Test")
| written _ |> _