feat(01-03): Channel Gateway (Slack adapter) and Message Router
- gateway/normalize.py: normalize_slack_event -> KonstructMessage (strips bot mention)
- gateway/channels/slack.py: register_slack_handlers for app_mention + DM events
- rate limit check -> ephemeral rejection on exceeded
- idempotency dedup (Slack retry protection)
- placeholder 'Thinking...' message posted in-thread before Celery dispatch
- auto-follow engaged threads with 30-minute TTL
- HTTP 200 returned immediately; all LLM work dispatched to Celery
- gateway/main.py: FastAPI on port 8001, /slack/events + /health
- router/tenant.py: resolve_tenant workspace_id -> tenant_id (RLS-bypass query)
- router/ratelimit.py: check_rate_limit Redis token bucket, RateLimitExceeded exception
- router/idempotency.py: is_duplicate + mark_processed (SET NX, 24h TTL)
- router/context.py: load_agent_for_tenant with RLS ContextVar setup
- orchestrator/tasks.py: handle_message now extracts placeholder_ts/channel_id,
calls _update_slack_placeholder via chat.update after LLM response
- docker-compose.yml: gateway service on port 8001
- pyproject.toml: added redis, konstruct-router, konstruct-orchestrator deps
Adolfo Delorenzo
6f30705e1a