oikos phase 0: ontology + inventory + policy seeds, OpenAPI contract, ADRs

- seeds/ontology.yaml: 59 entity types (5 abstract, is-a hierarchy), 46
  relationship types with cardinality, 6 lifecycles with terminal states
  and named precondition checks
- seeds/inventory.yaml: 110 entities / 142 relationships translated from
  legacy inventory.yaml (fleet, services, ingress, storage, governance,
  archaeology); thin spots marked for backfill
- seeds/policy.yaml: 4 risk classes, 27 approval rules (hierarchy-aware,
  per-entity overrides), autonomy kill-switch off (cold start)
- api/openapi.yaml: full v1 REST contract (40 paths), RFC 9457 errors,
  cursor pagination, idempotency, ETag/If-Match, scopes; redocly-clean
- docs/adr/0001-0010: initial architecture decision records
- scripts/validate-seeds.py: Phase 0 gate — hierarchy, lifecycles,
  endpoints, cardinality, policy cross-refs (0 errors)
- plan: layer CHECK gains 'meta' (root type), cardinality gains
  'many-to-one'

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/adr/0009-sse-over-websocket.md

@@ -0,0 +1,19 @@
+# ADR 0009 — SSE over WebSocket for the event stream
+
+Status: accepted (2026-07-07) · Plan: rev 3, R3-14
+
+## Context
+Live updates (signals, executions, approvals) push server→client only.
+Rev 2 specified WebSocket.
+
+## Decision
+Server-Sent Events at GET /api/v1/events/stream: plain HTTP (proxies
+through Caddy without upgrade handling), native browser EventSource with
+auto-reconnect, Last-Event-ID resume backed by the events table. Bounded
+per-subscriber buffers with drop-oldest; heartbeat comments every 15s.
+Delivery is best-effort — GET /events backfills. Transactional emission +
+post-commit LISTEN/NOTIFY feed the stream.
+
+## Consequences
+- No bidirectional channel; if one is ever needed (interactive terminals),
+  add WebSocket alongside — this ADR covers the event feed only.