Use `trace` for debugger events

^{Originally posted by **mooori** August 8, 2026}
After the removal of traces we turned debug traces into events:

https://github.com/0xMiden/compiler/blob/6195153c50b689648a635390e948496ce324c5f3/codegen/masm/src/events.rs#L19-L24

Only the `DebugExecutor` cares about these events. However, most `Host`s error on observing an event for which no handler is registered. So we added [no-op handlers](https://github.com/0xMiden/miden-vm/blob/next/crates/lib/core/src/handlers/readonly.rs) for these events to the core library.

In the meantime readonly events were added, called `trace` as well. We have two options now:

#### A) Keep regular events

Maintain the existing state, relying on the no-op handlers in core lib to avoid errors in hosts other than `DebugExecutor`.

- Pro: More efficient in terms of cycles
- Con: Relies on no-op handlers

#### B) Change to traces (readonly events)

Make the events above traces and remove the no-op handlers from the core library.

- Pro: Cleaner solution, not relying on no-op handlers
- Con: 2 extra cycles per trace compared to regular event