Add event, req, count, and relay commands

[kwsantiago]

Builds the client commands on top of libnostr-z 0.3.2.

Commands

• event <url> --sec <k> [-c content] [-k kind] [--ts unix] [-t name=value] [-p pubkey] - sign and publish an event, print it.
• req <url> [-k kind] [-a author] [-i id] [-l limit] [-t name=value] - subscribe, print matching events, exit at EOSE.
• count <url> [filters..] - NIP-45 count of matching events.
• relay <url> - fetch and print the NIP-11 relay information document.

req and count share filter parsing via parseQuery.

Verified live against wisp

• event produces valid signed events (id/pubkey/sig/tags) matching nak byte-for-byte.
• req returns clean event objects; tag filters work.
• count -k 1 and count -k 1 -t t=... return correct totals.
• relay returns a byte-identical NIP-11 document to a curl NIP-11 request.

Notes

• Pinned to libnostr-z v0.3.2 (NIP-45 count + NIP-11 fetch land there).
• sync (NIP-77) is still stubbed; it lands after the negentropy sync driver is added to libnostr-z.