fix(canvas): restore shipped policy/host-disable contracts; harden workspaces doctor cleanup (#110927)

* fix(dashboard): harden canvas and workspace compatibility

* docs(web): add dashboard architecture

* chore: remove release-owned changelog entry

* docs: update dashboard architecture map

docs/docs.json

@@ -1752,6 +1752,7 @@
                   "web/index",
                   "web/control-ui",
                   "web/dashboard",
+                  "web/dashboard-architecture",
                   "web/webchat",
                   "web/tui",
                   "web/lobster"