Fix iterator macro indentation bug

[BlakeASmith]

Fix iterator macros to correctly include all lines of an indented block within the generated loop.

The issue (CLI-34) was that iterator macros applied to indented blocks only included the first line of the block in the loop, leaving subsequent indented lines outside. This was due to the macro parser's find_target_for_macro() only identifying single lines and _apply_single_transformation() only replacing the first line. The fix extends the parser to detect and process multi-line indented blocks, ensuring all intended content is correctly looped.

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Linear Issue: CLI-34

[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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