Function detect_format 

pub fn detect_format(path: &str, content: &str) -> Result<ImportFormat>

Detect the import format from file extension and content.

Detection order:

1. .cast extension → error (asciinema not supported)
2. .sh or .bash extension → BashScript
3. Shebang lines (#!/bin/bash, #!/bin/sh, #!/usr/bin/env bash) → BashScript
4. Lines matching : TIMESTAMP:DURATION;CMD → ZshHistory
5. Lines starting with - cmd: → FishHistory
6. Default fallback → BashHistory

Errors

Returns an error if the file is an unsupported format (e.g., .cast files).

Panics

Panics if the internal regex pattern is invalid (should never happen).