Dynamic IO proxy: derive proxied primitives from component io_refs

Replace hardcoded IO primitive lists on both client and server with
data-driven registration. Page registry entries carry :io-deps (list
of IO primitive names) instead of :has-io boolean. Client registers
proxied IO on demand per page via registerIoDeps(). Server builds
allowlist from component analysis.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/sx/ref/orchestration.sx

@@ -648,7 +648,10 @@
                 (do (log-warn (str "sx:route target not found: " target-sel)) false)
                 (if (not (deps-satisfied? match))
                   (do (log-info (str "sx:route deps miss for " page-name)) false)
-                  (let ((has-io (get match "has-io")))
+                  (let ((io-deps (get match "io-deps"))
+                        (has-io (and io-deps (not (empty? io-deps)))))
+                    ;; Ensure IO deps are registered as proxied primitives
+                    (when has-io (register-io-deps io-deps))
                     (if (get match "has-data")
                       ;; Data page: check cache, else resolve asynchronously
                       (let ((cache-key (page-data-cache-key page-name params))
@@ -1024,6 +1027,8 @@
 ;;   (try-eval-content source env)  → DOM node or nil (catches eval errors)
 ;;   (try-async-eval-content source env callback) → void; async render,
 ;;     calls (callback rendered-or-nil). Used for pages with IO deps.
+;;   (register-io-deps names)       → void; ensure each IO name is registered
+;;     as a proxied IO primitive on the client. Idempotent.
 ;;   (url-pathname href)            → extract pathname from URL string
 ;;   (resolve-page-data name params cb) → void; resolves data for a named page.
 ;;     Platform decides transport (HTTP, cache, IPC, etc). Calls (cb data-dict)