fix(ts-sdk): fix nohup process completion detection and OSS download path

[xdlkc]

Summary

Fixes three bugs in the TS SDK's nohup/OSS download path that caused large file downloads to fail:

• waitForProcessCompletion misinterpreted "process exited" exceptions as failures (divergence from Python SDK behavior)
• ensureOssutil used normal mode which hits the 85s server-side run_in_session timeout
• oss_client.ts wget/ossutil cp used normal mode instead of nohup for long-running transfers

Changes

File	Change
client.ts	Distinguish timeout vs command-failure exceptions in waitForProcessCompletion
file_system.ts	ensureOssutil writes script to file + runs via nohup (matches Python process.execute_script)
oss_client.ts	Revert wget/ossutil cp to nohup mode with waitTimeout: 600
http.ts	Relax PID extraction regex (don't require PID_SUFFIX)

Test Plan

• 50MB file download via auto mode — MD5 verified
• 50MB file download via explicit --download-mode oss — MD5 verified
• Small file download via direct mode — content intact
• All 861 unit tests pass (npm run test:unit)

Fixes #1223

🤖 Generated with Claude Code

[Timandes]

Review note:

[P1] rock/ts-sdk/src/sandbox/oss_client.ts around the sandbox-side wget path: after switching wget to mode: 'nohup', sandbox.arun() only reports that the monitored process completed; it does not prove the wrapped wget command exited successfully. The current follow-up check only verifies that targetPath exists, so a failed or interrupted wget that leaves an empty/partial file can still make uploadViaOss() return success.

Please add a stronger verification step before returning success, for example compare stat -c %s '${targetPath}' with the local fileSize, or make the nohup wrapper persist and check the real command exit code. This matters because the signed URL download is now long-running and precisely the path where partial files are most likely to appear.

[Timandes]

Review note:

[P1] rock/ts-sdk/src/sandbox/file_system.ts in ensureOssutil() now does a quick check with this.sandbox.execute({ command: ['ossutil', 'version'], timeout: 60 }). When ossutil is not installed yet, the server executes this as subprocess.run([...]) with shell=false, so the missing executable raises FileNotFoundError. That gets wrapped as status=Failed, and the TS SDK execute() throws before this method can fall through to the install script.

This breaks the first-time install path that the PR is trying to fix. Please either remove the quick check, or make it non-throwing when the command is missing, e.g. run a shell/session check like command -v ossutil >/dev/null 2>&1 && ossutil version and catch failures so the install script still runs.