feat(router,cli): replyTo override + CLI admin-transport flows

- InboundEvent gains an optional replyTo; router stamps the row's address
  fields from it when set, so replies can route to a different channel than
  the one the inbound came in on.
- ChannelSetup adds onInboundEvent for admin-transport adapters that build
  the full event themselves.
- CLI wire format accepts {text, to, reply_to}. Routed messages go through
  onInboundEvent and do not evict an active chat client.
- init-first-agent hands the DM welcome to the running service via
  data/cli.sock — synchronous wake, no sweep wait. Fails loudly if the
  service is down; no silent fallback.
- Split the CLI scratch-agent bootstrap into scripts/init-cli-agent.ts;
  init-first-agent is DM-only.

Agents cannot set replyTo: it lives only on the inbound/router seam and is
consumed once when writing messages_in.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/index.ts

@@ -86,6 +86,15 @@ async function main(): Promise<void> {
           log.error('Failed to route inbound message', { channelType: adapter.channelType, err });
         });
       },
+      onInboundEvent(event) {
+        routeInbound(event).catch((err) => {
+          log.error('Failed to route inbound event', {
+            sourceAdapter: adapter.channelType,
+            targetChannelType: event.channelType,
+            err,
+          });
+        });
+      },
       onMetadata(platformId, name, isGroup) {
         log.info('Channel metadata discovered', {
           channelType: adapter.channelType,