node:diagnostics_channel: honor traceCallback position and arguments #3086

Summary

TracingChannel#traceCallback(fn, position, context, thisArg, ...args) should wrap the callback argument at the requested position while preserving all surrounding arguments. Perry currently ignores position and calls fn with a fixed (wrappedCallback, err, res) shape, so callback-last or callback-middle APIs receive the wrong arguments and extra arguments are dropped.

Node Behavior

Probe run with Node v25.9.0:

const { tracingChannel } = require("node:diagnostics_channel");
const ch = tracingChannel("tracecb-position");
const events = [];
ch.subscribe({
  start: (ctx) => events.push("start:" + JSON.stringify(ctx)),
  end: (ctx) => events.push("end:" + JSON.stringify(ctx)),
  asyncStart: (ctx) => events.push("asyncStart:" + JSON.stringify(ctx.result)),
  asyncEnd: (ctx) => events.push("asyncEnd:" + JSON.stringify(ctx.result)),
});
function target(a, cb, b, c) {
  events.push("fn args:" + [a, typeof cb, b, c].join(","));
  cb(null, "cb-value");
  return "target-ret";
}
const ret = ch.traceCallback(target, 1, { ctx: true }, { tag: "this" },
  "A", (err, value) => events.push("callback:" + err + ":" + value), "B", "C");
console.log("ret:", ret);
console.log(events.join("\n"));

Observed result:

ret: target-ret
start:{"ctx":true}
fn args:A,function,B,C
asyncStart:"cb-value"
callback:null:cb-value
asyncEnd:"cb-value"
end:{"ctx":true,"result":"cb-value"}

Perry Behavior

• docs/runtime-parity.md lists tracingChannel.traceCallback(fn[, position[, context[, thisArg[, ...args]]]]).
• crates/perry-runtime/src/node_submodules/diagnostics.rs::diag_trace_callback() takes fn_value, _position, context, this_arg, callback, err, and res.
• The _position argument is not used.
• The inactive path calls call_fn_value(fn_value, this_arg, &[callback, err, res]).
• The active path builds a wrapped callback and calls call_fn_value(fn_value, this_arg, &[wrapped_value, err, res]).
• Existing trace-callback fixtures only exercise position === 0.

Suggested PR Cut

Batch this with related issues in:
node:diagnostics_channel: tracing and store semantics parity cut (#3242)

Good batch candidates:

• node:diagnostics_channel: reject symbol tracingChannel names #3084
• node:diagnostics_channel: forward all runStores callback arguments #3082
• node:diagnostics_channel: preserve non-callable bindStore transform errors #3085

Do not batch with:

• node:trace_events category tracing
• generic Promise scheduler rewrites unless required by this diagnostics-specific behavior
• worker/thread diagnostics subscriber policy changes

Acceptance

• parity/regression test proves a non-zero callback position preserves arguments before and after the callback
• traceCallback() forwards all provided args rather than only a fixed (callback, err, res) shape
• current tracing event ordering and context.result / context.error updates remain Node-compatible
• inactive/no-subscriber fast path preserves the same argument behavior
• related known-failure/docs/manifest entries updated if touched