Support viewing the current stack frames of a snapshot dump

Right now, if you suspend a Monty VM at a host call, you only get the ability to see that function call (and resume execution). You can't inspect the current stack to provide debugging information about what is currently happening in the VM.

It would be great to have a public method on SyncSnapshot called snapshot.inspect() (or similar) that gives you back a list of Frame objects so you can see the current stack (similar to how exception traces have this information today). https://pydantic.dev/docs/monty/api/python/errors/#pydantic_monty.Frame

Also talked here about this: https://pydanticlogfire.slack.com/archives/C0AEZ9EQT0F/p1788983343955609