persistent auth in SQLite, API chat/logs, agent completion via channel

- Auth: move from state.json to SQLite authed_chats table, with memory cache
- Remove Persistent/state.json, all state now in noc.db
- HTTP API: POST /api/chat (end-to-end LLM), GET /api/logs (failed API requests)
- API logging: store raw request/response for 400 errors in api_log table
- Agent completion: spawn_agent sends LifeEvent::AgentDone via channel,
  life loop picks up with full conversation context and responds
- Config structs: derive Clone for HTTP server
- System prompt: instruct LLM not to add timestamps
- Makefile: rsync without --delete to preserve VPS-only tools

noc.service.in

@@ -12,7 +12,6 @@ RestartSec=5
 Environment=RUST_LOG=noc=info
 Environment=RUST_BACKTRACE=1
 Environment=NOC_CONFIG=@REPO@/config.yaml
-Environment=NOC_STATE=@REPO@/state.json
 Environment=PATH=@PATH@
 
 [Install]