#2628 feat: run-level ATIF trajectory loading for claude-code and codex

Summary

Follow-up to #2619: --load-trajectory now also accepts ATIF trajectories on job level.

Tested with

uv run harbor run -p examples/tasks/hello-load-atif-trajectory -a claude-code -m opus -e daytona --load-trajectory examples/tasks/hello-load-atif-trajectory/environment/trajectory.json
uv run harbor run -p examples/tasks/hello-load-atif-trajectory -a codex -m gpt-5.6-sol -e daytona --load-trajectory examples/tasks/hello-load-atif-trajectory/environment/trajectory.json
uv run harbor run -p examples/tasks/hello-load-atif-trajectory -a claude-code -m opus -e daytona --load-trajectory jobs/2026-08-05__12-09-06/hello-world__33pZzhH/agent/trajectory.json
uv run harbor run -p examples/tasks/hello-load-atif-trajectory -a codex -m gpt-5.6-sol -e daytona --load-trajectory jobs/2026-08-05__12-09-06/hello-world__33pZzhH/agent/trajectory.json

which means