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/icecast/module.json

@@ -4,10 +4,15 @@
   "capabilities": [
     "container-runtime"
   ],
+  "emits": [
+    "module.icecast.stream.started",
+    "module.icecast.stream.stopped"
+  ],
   "own-secrets": {
     "source": "/var/lib/icecast-module/source.secret",
     "admin": "/var/lib/icecast-module/admin.secret",
-    "relay": "/var/lib/icecast-module/relay.secret"
+    "relay": "/var/lib/icecast-module/relay.secret",
+    "broker": "/var/lib/icecast-module/broker"
   },
   "listens": [
     {