SDK Prompting for permissions to read an output file created by CLI for large outputs

```
{"type":"tool.execution_complete","data":{"toolCallId":"call_Gy2uDhKI9qIX2yMRS5USIm3C","....,"result":{"content":"Output too large to read at once (74.5 KB). Saved to: /var/folders/tk/xz6l8fxs0cxgphyh0xy2n4hh0000gn/T/copilot-tool-output-1776206629188-gotvti.txt\nConsider using tools like grep (for [\"ts\",\"js\",\"json\"]","matches_found":"true","large_output":"true","large_output_file":"/var/folders/tk/xz6l8fxs0cxgphyh0xy2n4hh0000gn/T/copilot-tool-output-1776206629188-gotvti.txt"},"
```

& then SDK passes permission request onto client to read this file.
CLI should auto approve such reads.

Start by tracing the CLI large-output handling from the point where the output is saved to a temporary file and the SDK forwards a read permission request to the client. Done means reads of these CLI-created output files are automatically approved without an additional client permission prompt.

Written by the indexing model from the issue text.