feat(cli): add amy CLI with Marmot subcommand surface

New :cli JVM module producing an `amy` binary that drives Amethyst
functionality headlessly. Identity and relay configuration sit at the
root (`amy init`, `amy whoami`, `amy relay …`); Marmot/MLS lives under
`amy marmot …` so future verbs (dm, feed, profile) can slot in cleanly.

Marmot surface covered:
- key-package publish / check
- group create / list / show / members / admins / add / rename /
  promote / demote / remove / leave
- message send / list (kind:9 inner events)
- await key-package / group / member / admin / message / rename / epoch
  (non-interactive polling with --timeout; exit 124 on timeout)

Wiring:
- NostrClient + BasicOkHttpWebSocket.Builder, reusing the existing
  publishAndConfirmDetailed and fetchFirst accessories
- MarmotManager from :commons with file-backed MlsGroupStateStore,
  KeyPackageBundleStore, and MarmotMessageStore (unencrypted — scratch
  harness use only)
- each invocation is one-shot: prepare → syncIncoming → run command →
  persist → disconnect

All commands emit one JSON object on stdout; diagnostics on stderr.
Designed so shell harnesses can pipe through jq without bespoke parsing.

https://claude.ai/code/session_01M6dCKAF5Y1VyHGZPjzwDXq

settings.gradle

@@ -37,3 +37,4 @@ include ':quartz'
 include ':commons'
 include ':ammolite'
 include ':desktopApp'
+include ':cli'