[bug] policy bypass gaps in block-rm-rf, block-curl-pipe-sh, and protect-env-vars #59

Three built-in policies have regex gaps that allow commands to slip through undetected.

1. block-rm-rf — GNU long flags bypass

The flag check only filters short flags (-r, -f). GNU long flags --recursive and --force are completely ignored.

Currently unblocked:

• rm --recursive --force /
• rm -r --force / (mixed)
• rm --recursive -f / (mixed)

2. block-rm-rf — depth-1 absolute path without trailing slash

hasDestructivePath only triggers on trailing /, /*, or ~. A bare top-level path without a trailing slash bypasses the gate entirely.

Currently unblocked:

• rm -rf /home
• rm -rf /etc
• rm --recursive --force /home

3. block-curl-pipe-sh — narrow shell list

Regex only covers sh|bash|zsh. Other common POSIX shells are not checked.

Currently unblocked:

• curl ... | fish
• curl ... | dash
• curl ... | ksh
• wget ... | ash

4. protect-env-vars — ${VAR} brace expansion bypass

ECHO_ENV_RE matches $[A-Za-z_] but not ${ — the brace falls outside the character class.

Currently unblocked:

• echo ${SECRET_KEY}
• echo ${HOME}/bin