Add reactive runtime demos + sx-web federation plan

7 interactive island demos for the reactive runtime layers:
- L0 Ref (timer + DOM handle), L1 Foreign (canvas via host-call),
  L2 Machine (traffic light), L3 Commands (undo/redo),
  L4 Loop (bouncing ball), L5 Keyed Lists, L6 App Shell

Fix OCaml build: add (wrapped false) to lib/dune, remove Sx. qualifiers.
Fix JS build: include dom-lib + browser-lib in adapter compilation.

New plan: sx-web federated component web — browser nodes via WebTransport,
server nodes via IPFS, in-browser authoring, AI composition layer.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sx/sx/nav-data.sx

@@ -257,7 +257,9 @@
   (dict :label "Isolated Evaluator" :href "/sx/(etc.(plan.isolated-evaluator))"
         :summary "Core/application split, shared sx-platform.js, isolated JS evaluator, Rust WASM via handle table. Only language-defining spec gets bootstrapped; everything else is runtime-evaluated .sx.")
   (dict :label "Mother Language" :href "/sx/(etc.(plan.mother-language))"
-        :summary "SX as its own compiler. OCaml as substrate (closest to CEK), Koka as alternative (compile-time linearity), ultimately self-hosting. One language, every target.")))
+        :summary "SX as its own compiler. OCaml as substrate (closest to CEK), Koka as alternative (compile-time linearity), ultimately self-hosting. One language, every target.")
+  (dict :label "sx-web" :href "/sx/(etc.(plan.sx-web))"
+        :summary "Federated component web. Browser nodes via WebTransport, server nodes via IPFS, content-addressed SX verified by CID. In-browser editing, testing, publishing. AI composition over the federated graph.")))
 
 (define reactive-examples-nav-items (list
   {:label "Counter" :href "/sx/(geography.(reactive.(examples.counter)))"}