Add hosted shell response stream events

[raashish1601]

Summary

• add the missing hosted-shell Responses stream event interfaces for
  esponse.shell_call_command.* and
  esponse.shell_call_output_content.*
• include them in ResponseStreamEvent, ResponsesServerEvent, and the generated export/docs index
• add a snapshot-backed ResponseStream regression covering the hosted-shell event sequence

Testing

• ./node_modules/.bin/jest tests/lib/ResponseStream.test.ts --runInBand
• ./node_modules/.bin/prettier --check --end-of-line lf src/resources/responses/responses.ts src/resources/responses/api.md tests/lib/ResponseStream.test.ts
• ./node_modules/.bin/eslint src/resources/responses/responses.ts tests/lib/ResponseStream.test.ts

Fixes #1750.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Mark shell command obfuscation as optional

ResponseShellCallCommandDeltaEvent declares obfuscation as a required string, but Responses.StreamOptions.include_obfuscation in the same file documents that obfuscation fields can be disabled to reduce bandwidth. In that mode, response.shell_call_command.delta events may not carry this field, so consumers relying on this type can incorrectly assume it is always present and hit runtime undefined access. Model obfuscation as optional (or nullable) to keep the event type aligned with the documented stream option.

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