fix: wire v2 setup flow — barrel import, registration, verification

- Import channel barrel from src/index.ts so channel skills that
  uncomment lines in src/channels/index.ts actually execute
- Rewrite setup/register.ts to create v2 entities (agent_groups,
  messaging_groups, messaging_group_agents) in data/v2.db instead
  of v1's store/messages.db
- Fix setup/verify.ts to check v2 central DB for registered groups
- Add prominent "MESSAGE DROPPED" warnings in router when no agent
  groups are wired, with actionable guidance

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/router.ts

@@ -58,8 +58,11 @@ export async function routeInbound(event: InboundEvent): Promise<void> {
   // 2. Resolve agent group via messaging_group_agents
   const agents = getMessagingGroupAgents(mg.id);
   if (agents.length === 0) {
-    log.warn('No agent groups configured for messaging group', {
+    // This is a common fresh-install issue: channels work but no agent group
+    // is wired to handle messages. Run setup/register to create the wiring.
+    log.warn('MESSAGE DROPPED — no agent groups wired to this channel. Run setup register step to configure.', {
       messagingGroupId: mg.id,
+      channelType: event.channelType,
       platformId: event.platformId,
     });
     return;
@@ -68,7 +71,10 @@ export async function routeInbound(event: InboundEvent): Promise<void> {
   // Pick the best matching agent (highest priority, trigger matching in future)
   const match = pickAgent(agents, event);
   if (!match) {
-    log.debug('No agent matched for message', { messagingGroupId: mg.id });
+    log.warn('MESSAGE DROPPED — no agent matched trigger rules', {
+      messagingGroupId: mg.id,
+      channelType: event.channelType,
+    });
     return;
   }