fix(cli): preserve subscription API errors

[mnebliienko]

Problem

Subscription commands replaced API error codes with generic command errors and added empty details to delegated fetch errors.

Change

• Preserve API error code, message, and status.
• Use stable command-specific codes for non-API failures.
• Leave delegated fetch errors unchanged.

Verification

• Focused subscription tests: 22 passed.
• Full CLI suite: 1,078 passed, 1 skipped.
• TypeScript, ESLint, Prettier, and TypeDoc passed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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