feat(a2a): multi-client support for daemon #586
Description
Parent
Part of #581. Follow-up, deferred from MVP.
Summary
Support multiple TUI/API clients connecting to a single daemon simultaneously. Map context_id to separate Agent instances with independent conversation state.
Scope
- Agent pool or per-context-id agent factory
- Concurrent request handling (remove single-client serialization)
- Context isolation: each client gets independent memory/conversation
- Resource limits: max concurrent clients, context TTL
Notes
Not in scope for initial release. Current MVP supports one client at a time with serialized requests via LoopbackChannel.