feat: add headers to all responses

[drish]

Summary by cubic

Add HTTP response headers to all JSON object responses by injecting a headers field into the returned dict. Clients can read x-request-id and rate limit info without breaking existing code; top-level list responses are unchanged.

• New Features
  • Capture response headers and include them under headers in all dict responses.
  • Introduced BaseResponse TypedDict and updated all response types to inherit it (headers is optional and type-safe).
  • Added usage example and integration test for headers access.

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