Fix effect SSR: rebind after file load instead of guarding spec

Revert (when (client?) ...) guard in signals.sx — it broke JS tests
since client? is false in Node.js too.

Instead, rebind effect and register-in-scope as no-ops in sx_server.ml
AFTER all .sx files load. The SX definition from signals.sx is replaced
only in the OCaml SSR context. JS tests and WASM browser keep the real
effect implementation.

Remove redundant browser primitive stubs from sx_primitives.ml — only
resource SSR stub needed (effect override moved to server setup).

JS tests: 1582/1585 (3 VM closure interop remain)

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

shared/static/wasm/sx/signals.sxbc

@@ -1,3 +1,3 @@
 (sxbc 1 "7e4a727b2f55684e"
   (code
-    :constants ("with-marsh-scope" {:upvalue-count 0 :arity 2 :constants ("list" "with-island-scope" {:upvalue-count 1 :arity 1 :constants ("append!") :bytecode (20 0 0 18 0 16 0 49 2 50)} "dom-set-data" "sx-marsh-disposers") :bytecode (52 0 0 0 17 2 20 1 0 51 2 0 1 2 16 1 48 2 5 20 3 0 16 0 1 4 0 16 2 49 3 50)} "dispose-marsh-scope" {:upvalue-count 0 :arity 1 :constants ("dom-get-data" "sx-marsh-disposers" "for-each" {:upvalue-count 0 :arity 1 :constants ("cek-call") :bytecode (20 0 0 16 0 2 49 2 50)} "dom-set-data") :bytecode (20 0 0 16 0 1 1 0 48 2 17 1 16 1 33 24 0 51 3 0 16 1 52 2 0 2 5 20 4 0 16 0 1 1 0 2 49 3 32 1 0 2 50)} "emit-event" {:upvalue-count 0 :arity 3 :constants ("dom-dispatch") :bytecode (16 0 16 1 16 2 52 0 0 3 50)} "on-event" {:upvalue-count 0 :arity 3 :constants ("dom-on") :bytecode (20 0 0 16 0 16 1 16 2 49 3 50)} "bridge-event" {:upvalue-count 0 :arity 4 :constants ("effect" {:upvalue-count 4 :arity 0 :constants ("dom-on" {:upvalue-count 2 :arity 1 :constants ("event-detail" "cek-call" "list" "reset!") :bytecode (16 0 52 0 0 1 17 1 18 0 33 16 0 20 1 0 18 0 16 1 52 2 0 1 48 2 32 2 0 16 1 17 2 20 3 0 18 1 16 2 49 2 50)}) :bytecode (20 0 0 18 0 18 1 51 1 0 0 2 0 3 48 3 17 0 16 0 50)}) :bytecode (51 1 0 1 0 1 1 1 3 1 2 52 0 0 1 50)} "resource" {:upvalue-count 0 :arity 1 :constants ("signal" "dict" "loading" "data" "error" "promise-then" "cek-call" {:upvalue-count 1 :arity 1 :constants ("reset!" "dict" "loading" "data" "error") :bytecode (20 0 0 18 0 1 2 0 4 1 3 0 16 0 1 4 0 2 52 1 0 6 49 2 50)} {:upvalue-count 1 :arity 1 :constants ("reset!" "dict" "loading" "data" "error") :bytecode (20 0 0 18 0 1 2 0 4 1 3 0 2 1 4 0 16 0 52 1 0 6 49 2 50)}) :bytecode (20 0 0 1 2 0 3 1 3 0 2 1 4 0 2 52 1 0 6 48 1 17 1 20 6 0 16 0 2 48 2 51 7 0 1 1 51 8 0 1 1 52 5 0 3 5 16 1 50)}) :bytecode (51 1 0 128 0 0 5 51 3 0 128 2 0 5 51 5 0 128 4 0 5 51 7 0 128 6 0 5 51 9 0 128 8 0 5 51 11 0 128 10 0 50)))
+    :constants ("with-marsh-scope" {:upvalue-count 0 :arity 2 :constants ("list" "with-island-scope" {:upvalue-count 1 :arity 1 :constants ("append!") :bytecode (20 0 0 18 0 16 0 49 2 50)} "dom-set-data" "sx-marsh-disposers") :bytecode (52 0 0 0 17 2 20 1 0 51 2 0 1 2 16 1 48 2 5 20 3 0 16 0 1 4 0 16 2 49 3 50)} "dispose-marsh-scope" {:upvalue-count 0 :arity 1 :constants ("dom-get-data" "sx-marsh-disposers" "for-each" {:upvalue-count 0 :arity 1 :constants ("cek-call") :bytecode (20 0 0 16 0 2 49 2 50)} "dom-set-data") :bytecode (20 0 0 16 0 1 1 0 48 2 17 1 16 1 33 24 0 51 3 0 16 1 52 2 0 2 5 20 4 0 16 0 1 1 0 2 49 3 32 1 0 2 50)} "emit-event" {:upvalue-count 0 :arity 3 :constants ("dom-dispatch") :bytecode (20 0 0 16 0 16 1 16 2 49 3 50)} "on-event" {:upvalue-count 0 :arity 3 :constants ("dom-on") :bytecode (20 0 0 16 0 16 1 16 2 49 3 50)} "bridge-event" {:upvalue-count 0 :arity 4 :constants ("effect" {:upvalue-count 4 :arity 0 :constants ("dom-on" {:upvalue-count 2 :arity 1 :constants ("event-detail" "cek-call" "list" "reset!") :bytecode (20 0 0 16 0 48 1 17 1 18 0 33 16 0 20 1 0 18 0 16 1 52 2 0 1 48 2 32 2 0 16 1 17 2 20 3 0 18 1 16 2 49 2 50)}) :bytecode (20 0 0 18 0 18 1 51 1 0 0 2 0 3 48 3 17 0 16 0 50)}) :bytecode (51 1 0 1 0 1 1 1 3 1 2 52 0 0 1 50)} "resource" {:upvalue-count 0 :arity 1 :constants ("signal" "dict" "loading" "data" "error" "promise-then" "cek-call" {:upvalue-count 1 :arity 1 :constants ("reset!" "dict" "loading" "data" "error") :bytecode (20 0 0 18 0 1 2 0 4 1 3 0 16 0 1 4 0 2 52 1 0 6 49 2 50)} {:upvalue-count 1 :arity 1 :constants ("reset!" "dict" "loading" "data" "error") :bytecode (20 0 0 18 0 1 2 0 4 1 3 0 2 1 4 0 16 0 52 1 0 6 49 2 50)}) :bytecode (20 0 0 1 2 0 3 1 3 0 2 1 4 0 2 52 1 0 6 48 1 17 1 20 5 0 20 6 0 16 0 2 48 2 51 7 0 1 1 51 8 0 1 1 48 3 5 16 1 50)}) :bytecode (51 1 0 128 0 0 5 51 3 0 128 2 0 5 51 5 0 128 4 0 5 51 7 0 128 6 0 5 51 9 0 128 8 0 5 51 11 0 128 10 0 50)))