Fix sandbox HF_TOKEN not available inside container

Improve agent loop, tools, and research subagent for long-running autonomous tasks

fix: move import/signature validation to sandbox, keep host-side lightweight

Improve tool output quality: ANSI stripping, tail-biased truncation, noise suppression

feat: cancel sandbox creation on user interrupt

feat: kill sandbox processes and cancel HF jobs on user interrupt

fix: retry sandbox API calls on transient failures

chore: double sandbox command timeouts

stream sandbox creation logs to tool output, fix hf_jobs final status race

fix: route all HF token usage through session.hf_token from OAuth

fix: remove TRANSFORMERS_VERBOSITY from sandbox env

feat: restore sandbox tools and proactive compaction

feat: merge HF Space improvements

v3 prompt and tool desc rework

sandbox working and agent can use it

sandbox start