fix(hooks): use strings for binary file scanning in pre-push

[John-David Dalton (jdalton)]

Summary

• Use strings command for binary files (WASM, .lockb, etc) instead of raw grep to properly detect embedded paths and secrets
• Detect binary vs text using grep -qI, then extract printable strings before running pattern checks
• Add -- to grep for private key pattern to prevent dash-prefixed patterns being parsed as options

Test plan

• Verify pre-push hook passes on clean push
• Verify hook catches hardcoded paths in binary files