EventBuilder silently drops p tags whose value equals the signer's own
pubkey (NIP self-tagging suppression, enabled by default). The test was
using owner.public_key().to_hex() as the p tag value, so the tag was
stripped before signing and the event arrived at the relay with no p tag
at all — the validator always saw a clean envelope and the rejection was
never exercised.
Fix: generate a separate Keys pair for the p tag value so it survives
EventBuilder's self-tag filter and reaches the relay's validator.
Co-authored-by: Will Pfleger <pfleger.will@gmail.com>
Signed-off-by: Will Pfleger <pfleger.will@gmail.com>