pi-guardrails v0.15.0

9f0d736: Add a “decline and stop” option to the permission-gate prompt. Choosing it (press s, or select “Decline and stop” in the RPC fallback) blocks the dangerous command, emits a guardrails:action:blocked event with the new user-stop block source, and aborts the current agent turn so the assistant does not keep going.

09934f0: Update AGENTS.md to reflect the current three-extension layout and remove the unused, broken test harness.