Adds the ephemeral host-issued admin command event nostrnests uses
for kick (and future moderation actions like mute/ban):
AdminCommandEvent — kind 4312. Carries one Action (currently just
KICK) in `content`, an `a`-tag pointing at the room (kind-30312
address), and a `p`-tag for the target. The verb-in-content shape
lets us extend with new actions without a wire schema bump.
AdminCommandEvent.kick(roomATag, target) — builder.
AdminCommandEvent.action() / .targetPubkey() / .room() — accessors
for the recipient side. Unknown actions return null (forward-compat
with verbs not yet in the enum).
EventFactory — registered so LocalCache + Filter.match can decode
incoming events properly.
Authority enforcement is the CLIENT'S job — the relay just stores
and forwards. Recipients filter on `kinds=[4312], #a=[room],
#p=[me]` and only honour commands whose signer is a participant
marked HOST or MODERATOR on the active kind-30312. The next commit
wires that gating + the disconnect side effect into AudioRoomViewModel.
Tests:
* Build a kick template and verify the action/address/target tags
* Round-trip parse exposes room, target pubkey and action
* Unknown verb in `content` returns null from action()
* Missing tags return null from accessors (no throw)
Claude
7f5133a08f