nomos+web: streaming, provider routing, event gap-fill, embedded UI; fix approval FK & session context

Agent (cmd/nomos):
- Stream LLM tokens via NewStreaming; emit text_delta then final text.
- OpenRouter provider routing: data_collection=deny (ZDR) + require_parameters;
  NOMOS_PROVIDER_SORT opt-in; Exacto via model suffix.
- Multi-turn: reload session history into context; UI passes session id.
- Fix agent_activity logging (agent_id/session_id) and mcpClient data race.

Events (live control-room feed):
- approval.created (mcp), approval.decided (api), execution.completed/failed
  (approved-action path), signal.raised/resolved + health.changed (scheduler,
  transition-gated).

Fixes:
- createApproval FK violation (reuse execution entity) — the agent's only
  write path; log the previously-swallowed errors.

Web UI:
- Embed web/dist via //go:embed (single binary); Dockerfile builds SPA into
  the Go stage; committed .gitkeep placeholder keeps backend-only builds green.
- Caddy: Authentik-gated /agent/* -> nomos so the UI reaches the agent
  same-origin in production.

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

compose/caddy/Caddyfile.oikos

@@ -11,6 +11,13 @@ oikos.hubris.network {
     handle @enroll {
         reverse_proxy <mac-mini-mesh-ip>:8090
     }
+    # Nomos agent, same-origin for the control-room UI (EventSource/fetch can't
+    # set cross-origin auth headers). Authentik gates it; handle_path strips
+    # the /agent prefix so /agent/chat -> nomos /chat.
+    handle_path /agent/* {
+        import authentik
+        reverse_proxy <mac-mini-mesh-ip>:8092
+    }
     handle {
         import authentik
         reverse_proxy <mac-mini-mesh-ip>:8090