fix: strict mode, test stubs, pagination counts, N+1 queries, CSP hardening
- Enable TypeScript strict mode and fix all resulting type errors
- Add auth test stubs for requireRole and safeCompare
- Add proper COUNT(*) pagination totals to agents, tasks, notifications,
messages, conversations, and standup history endpoints
- Fix N+1 queries by hoisting db.prepare() outside loops in agents,
activities, notifications, conversations, standup, gateway health,
and notification delivery routes
- Remove unsafe-eval from CSP script-src directive
- Remove deprecated X-XSS-Protection header
bf0df9b6d0