fix(shell-local): avoid ETXTBSY for inline scripts

[tanmay-hc]

Summary

Update the default Unix execution path for generated shell-local inline scripts to invoke the configured inline_shebang interpreter instead of executing the temporary script directly.

Linux can reject direct execution with ETXTBSY (Text file busy) when the script is briefly held open for writing by the filesystem or another process. Invoking the interpreter causes it to read the script instead, avoiding that executable-file restriction.

Compatibility

• Preserves custom execute_command values.
• Preserves the configured inline_shebang and its arguments.
• Keeps the existing direct execution behavior for user-supplied script and scripts.
• Leaves Windows behavior unchanged.

[Copilot]

Pull request overview

Updates shell-local’s default Unix execution flow for generated inline scripts to avoid ETXTBSY by invoking the configured inline_shebang interpreter to read the temp script rather than executing the temp script directly.

Changes:

• Adjusts Validate to choose a different default execute_command on Unix when Inline/Command is used, invoking inline_shebang with the script path passed as $0.
• Adds unit tests validating the default execute_command selection across config modes (inline/command/script/custom).
• Adds an integration-style communicator test that runs an inline script while the script file is still open for writing.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
shell-local/config.go	Changes default Unix execute_command for inline/command to run via inline_shebang interpreter to avoid ETXTBSY.
shell-local/config_test.go	Adds table-driven coverage for Validate default execute_command behavior.
shell-local/communicator_test.go	Adds regression test ensuring inline execution works when the script file remains open for writing.

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