Refactoring2/iterator pattern/run

[NimishaShrivastava-dev]

Converted the run resource listing methods to use the Iterator pattern instead of returning ModelList objects.

Changes

Updated Runs.list() to return Iterator[Run]
Updated Runs.list_for_organization() to return Iterator[Run]
Both methods now use the internal _list() helper for pagination
Updated examples/run.py to convert iterators to lists where needed
Updated unit tests to mock _list() and verify data transformation
Testing

All 396 tests pass
No breaking changes to public API
Models remain unchanged for backward compatibility
Related

Aligns with iterator pattern used in policy_evaluation and oauth_token resources

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