s4nj1th/secr-cli ? reverse-engineered prompt

Build me a fast command line tool that scans a Git repository for secrets like API keys, tokens, passwords, and private keys. It should be written in Go and feel lightweight, but still do a thorough job by checking the repo quickly with concurrent scanning. I want it to respect .gitignore by default, support scanning only staged changes for pre commit use, and also be able to scan the whole repo when I need it.

Please include a simple way to print findings in a human readable format and as JSON for CI use. It should show severity levels like high, medium, and low, and have a command to list the rules it knows about. I also want basic Git integration, so it can install a pre commit hook and optionally run Git commands through the scanner before they go through. If you need to look up current Go or CLI docs online, go ahead and do that.