fix(cli): execute crashes with 'str' object has no attribute 'get'

[tengxiaoliu]

Summary

vastai execute <id> <command> crashes on every successful invocation with:

AttributeError: 'str' object has no attribute 'get'

Root cause

vastai/api/instances.py::execute() already polls the result URL internally and returns the command output as a str on success (or the raw response dict on failure, when there is no result_url).

The CLI handler vastai/cli/commands/misc.py::execute() was never updated for this. It still assumes the old dict shape — calling rj.get("success") and re-polling rj["result_url"] / rj["writeable_path"]. On the success path rj is a str, so .get() raises immediately, and the polling loop below it is now dead code (the API layer already polled).

The sibling logs() handler in the same file already handles the str return correctly via isinstance(rj, str) — execute() was simply missed in the refactor.

What it does

Removes the redundant dict-based polling in the CLI handler and prints what instances_api.execute() returns (str output on success, error dict otherwise). One file changed, −11 / +6.

Test plan

Verified against current master (before vs. after the change):

Command	Before	After
vastai execute <id> 'ls /workspace/...'	crash	prints listing
vastai execute <id> 'du -d1 -h /workspace/...'	crash	prints usage

The crash is in command-independent code (after the result is fetched), so it affects every successful execute, including rm.