Removes the `-i`/`--interactive` CLI flag and live file-based
recording. Instead, the REPL now supports a `/load <path>` command
to run scripts from disk, and `/save` to export the in-memory
session recording.
The `Recorder` is simplified to be purely in-memory, and the script
runtime is moved to `src/script/Runtime.zig`.
BREAKING CHANGE: The `-i`/`--interactive` flag has been removed. Use
the `/save` and `/load` commands within the REPL instead.