multistreaming: scenes/composition, installer build support, service updates

- multistreaming (new): RTMP ingest + multi-platform fan-out with pluggable providers (Twitch/YouTube/Kick/custom), zero-knowledge key vaults, Authelia OIDC auth, shared rooms with editor/streamer roles, single-use invites, per-account streaming grants, and scenes & composition (grid/PiP layouts, text/image overlays, per-output audio routing).
- installer: support Dockerfile build in metadata (not just image) and RSA key generation for the Authelia OIDC JWKS.
- authelia: add OIDC provider with portainer + multistreaming clients (public + PKCE).
- services: remove allprox; add nginx-proxy-manager and portainer; update lldap; regenerate catalog.

services/catalog.json

@@ -1,20 +1,30 @@
 {
-  "generatedAt": "2026-09-01T16:20:56.550Z",
+  "generatedAt": "2026-09-02T16:59:46.903Z",
   "services": [
-    {
-      "id": "allprox",
-      "version": "1.0.0",
-      "path": "services/allprox/metadata.json"
-    },
     {
       "id": "authelia",
-      "version": "1.0.0",
+      "version": "3.0.0",
       "path": "services/authelia/metadata.json"
     },
     {
       "id": "lldap",
       "version": "1.0.0",
       "path": "services/lldap/metadata.json"
+    },
+    {
+      "id": "multistreaming",
+      "version": "4.1.0",
+      "path": "services/multistreaming/metadata.json"
+    },
+    {
+      "id": "nginx-proxy-manager",
+      "version": "1.0.0",
+      "path": "services/nginx-proxy-manager/metadata.json"
+    },
+    {
+      "id": "portainer",
+      "version": "1.0.0",
+      "path": "services/portainer/metadata.json"
     }
   ]
 }