searxng, icecast, photos: full nox modules (ADR 0044/0046)

searxng: a search tool — tools-only, a stateless search has nothing to observe.
icecast: status tool, emits stream.started/.stopped by diffing live mountpoints.
photos: status/albums/recent tools, emits item.added (immich-shaped API, coded
defensively since the stub ships a placeholder image — flagged in the code).
Typecheck; manifests parse.

modules/photos/module.json

@@ -15,6 +15,12 @@
   "secrets": {
     "s3-bucket": "/etc/photos/store.secret"
   },
+  "emits": [
+    "module.photos.item.added"
+  ],
+  "own-secrets": {
+    "broker": "/etc/photos/broker"
+  },
   "resources": [
     {
       "id": "config",