The regex `ignore\s+(previous|all|above|prior)\s+instructions` only
allowed ONE word between "ignore" and "instructions". Multi-word
variants like "Ignore ALL prior instructions" bypassed the scanner
because "ALL" matched the alternation but then `\s+instructions`
failed to match "prior".
Fix: use `(?:\w+\s+)*` groups to allow optional extra words before
and after the keyword alternation.
