v2 phase 1: foundation — types, DB layer, logging

Add the v2 data layer: typed interfaces, central DB with migration
runner, per-entity CRUD, and agent-runner session DB operations.

- src/log.ts: concise message-first logging API
- src/types-v2.ts: AgentGroup, MessagingGroup, Session, MessageIn/Out
- src/db/: connection (WAL), migration runner, 001-initial schema,
  CRUD for agent_groups, messaging_groups, sessions, pending_questions
- container/agent-runner/src/db/: session DB connection, messages_in
  reads + status transitions, messages_out writes
- 31 new tests, all 277 tests pass

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

src/db/index.ts

@@ -0,0 +1,37 @@
+export { initDb, initTestDb, getDb, closeDb } from './connection.js';
+export { runMigrations } from './migrations/index.js';
+export {
+  createAgentGroup,
+  getAgentGroup,
+  getAgentGroupByFolder,
+  getAllAgentGroups,
+  getAdminAgentGroup,
+  updateAgentGroup,
+  deleteAgentGroup,
+} from './agent-groups.js';
+export {
+  createMessagingGroup,
+  getMessagingGroup,
+  getMessagingGroupByPlatform,
+  getAllMessagingGroups,
+  updateMessagingGroup,
+  deleteMessagingGroup,
+  createMessagingGroupAgent,
+  getMessagingGroupAgents,
+  getMessagingGroupAgent,
+  updateMessagingGroupAgent,
+  deleteMessagingGroupAgent,
+} from './messaging-groups.js';
+export {
+  createSession,
+  getSession,
+  findSession,
+  getSessionsByAgentGroup,
+  getActiveSessions,
+  getRunningSessions,
+  updateSession,
+  deleteSession,
+  createPendingQuestion,
+  getPendingQuestion,
+  deletePendingQuestion,
+} from './sessions.js';