[chore] Add secret redaction patterns for Slack, Stripe, npm

[fagemx]

crates/edda-bridge-claude/src/redact.rs covers API keys, GitHub/GitLab tokens, AWS keys, Bearer tokens.

Missing patterns for:

• Slack tokens (xoxb-, xoxp-)
• Stripe keys (sk_live_, pk_live_)
• npm tokens (npm_)