## What?
Fixed error handling in `insert_history_lines_to_writer` where all
terminal operations were silently ignoring errors via `.ok()`.
## Why?
Silent I/O failures could leave the terminal in an inconsistent state
(e.g., scroll region not reset) with no way to debug. This violates Rust
error handling best practices.
## How?
- Changed function signature to return `io::Result<()>`
- Replaced all `.ok()` calls with `?` operator to propagate errors
- Added `tracing::warn!` in wrapper function for backward compatibility
- Updated 15 test call sites to handle Result with `.expect()`
## Testing
- ✅ Pass all tests
## Type of Change
- [x] Bug fix (non-breaking change)
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Signed-off-by: Huaiwu Li <lhwzds@gmail.com>
Co-authored-by: Eric Traut <etraut@openai.com>
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