feat(dev-server): load the authz catalog at boot

Adds loadAppAuthzCatalog(appDir) to @wrnexus/dev-server: discovers
app/authz/*.ts declarations via buildRouter, imports and merges them
into an AuthzCatalog, returning an empty catalog when the app has no
declarations. A declaration with no default export is skipped with a
warning; a genuine conflict between two declarations throws
WRN-AUTHZ-CONFLICT naming both source files.

Declared the missing @wrnexus/authz workspace dependency in
dev-server's package.json.

packages/dev-server/package.json

@@ -8,6 +8,7 @@
     "./serve-entry": "./src/serve-entry.ts"
   },
   "dependencies": {
+    "@wrnexus/authz": "workspace:*",
     "@wrnexus/core": "workspace:*",
     "@wrnexus/dev-toolbar": "workspace:*",
     "@wrnexus/router": "workspace:*",