refactor: split web frontend + gateway out to uniweb app (bump 0.13.0)

The SPA (web/) and the web gateway (cmd/webgw) move to a dedicated app
projects/message_bus/apps/uniweb (its own Gitea sub-repo). unibus is now
strictly the bus plane: membership/keys, the client library and demo peers.
uniweb consumes unibus as a Go module via replace => ../unibus.

No capability lost; same SPA and gateway, in their own service folder.
go build/vet/test green after extraction.

web/node_modules/.pnpm-workspace-state-v1.json

@@ -0,0 +1,41 @@
+{
+  "lastValidatedTimestamp": 1781378216062,
+  "projects": {
+    "/home/enmanuel/fn_registry/projects/message_bus/apps/unibus/web": {
+      "name": "unibus-web",
+      "version": "0.1.0"
+    }
+  },
+  "pnpmfiles": [],
+  "settings": {
+    "allowBuilds": {
+      "esbuild": true
+    },
+    "autoInstallPeers": true,
+    "catalogs": {},
+    "dedupeDirectDeps": false,
+    "dedupeInjectedDeps": true,
+    "dedupePeerDependents": true,
+    "dedupePeers": false,
+    "dev": true,
+    "excludeLinksFromLockfile": false,
+    "hoistPattern": [
+      "*"
+    ],
+    "hoistWorkspacePackages": true,
+    "injectWorkspacePackages": false,
+    "linkWorkspacePackages": false,
+    "minimumReleaseAge": 1440,
+    "minimumReleaseAgeIgnoreMissingTime": true,
+    "nodeLinker": "isolated",
+    "optional": true,
+    "peersSuffixMaxLength": 1000,
+    "preferWorkspacePackages": false,
+    "production": true,
+    "publicHoistPattern": [],
+    "workspacePackagePatterns": [
+      "."
+    ]
+  },
+  "filteredInstall": false
+}