refactor(architecture): add DI container and lifecycle orchestration

[OneStepAt4time]

Summary

• implement issue refactor(architecture): introduce DI container and formalize service lifecycle #1622 by introducing ServiceContainer with explicit registration and dependency resolution (topological startup)
• refactor core service wiring in server.ts for TmuxManager, SessionManager, AuthManager, ChannelManager, and SessionMonitor via lifecycle adapters
• add startup health gate before listenWithRetry and reverse-order timeout-aware shutdown via container lifecycle management
• document the service dependency graph in architecture docs and add focused container lifecycle tests

Validation

• npm run lint
• npm run build
• npx tsc --noEmit
• npm test

Closes #1622