fix(cli): disable ssh connection sharing for sandbox sessions

[ericcurtin]

Summary

Turn off ssh connection sharing for every sandbox session so a user's ControlMaster config cannot route one sandbox into another.

Related Issue

Closes #3935

Changes

• Add sandbox_ssh_args in openshell-core with the shared ssh options, now including ControlMaster=no, ControlPath=none, ControlPersist=no.
• Use it in the CLI and the three duplicated option lists in the TUI.
• Forward command keeps only ForkAfterAuthentication=no.

Testing

• Checks appropriate to the affected code and behavior pass
• Unit tests added/updated (if applicable)
• E2E tests added/updated (if applicable)

cargo clippy and cargo test for openshell-core, openshell-cli (lib and lifecycle integration) and openshell-tui. New tests resolve ssh -G against a config with ControlMaster auto.

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)

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[ericcurtin]

If useful, please also try https://github.com/llmmanorg/llmman, which can launch agents in an OpenShell sandbox (--sandbox openshell).

[ericcurtin]

@krishicks @drew PTAL when you get a chance, and /ok to test 8bcba8e8db1fbd969c358638431c3de802175fdc if it looks good. Thank you!