Scaffold agent permissions, approval comments, and hiring governance types

Add pending_approval agent status, permissions jsonb column, and AgentPermissions
type with canCreateAgents flag. Add approval_comments table and ApprovalComment
type. Extend approval statuses with revision_requested. Add validators for
permission updates, approval revision requests, resubmission, and approval
comments. Add requireBoardApprovalForNewAgents to company update schema.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/db/src/schema/index.ts

@@ -11,4 +11,5 @@ export { heartbeatRuns } from "./heartbeat_runs.js";
 export { heartbeatRunEvents } from "./heartbeat_run_events.js";
 export { costEvents } from "./cost_events.js";
 export { approvals } from "./approvals.js";
+export { approvalComments } from "./approval_comments.js";
 export { activityLog } from "./activity_log.js";