Add :effects annotations to all spec files and update bootstrappers

Bootstrappers (bootstrap_py.py, js.sx) now skip :effects keyword in
define forms, enabling effect annotations throughout the spec without
changing generated output.

Annotated 180+ functions across 14 spec files:
- signals.sx: signal/deref [] pure, reset!/swap!/effect/batch [mutation]
- engine.sx: parse-* [] pure, morph-*/swap-* [mutation io]
- orchestration.sx: all [mutation io] (browser event binding)
- adapter-html.sx: render-* [render]
- adapter-dom.sx: render-* [render], reactive-* [render mutation]
- adapter-sx.sx: aser-* [render]
- adapter-async.sx: async-render-*/async-aser-* [render io]
- parser.sx: all [] pure
- render.sx: predicates [] pure, process-bindings [mutation]
- boot.sx: all [mutation io] (browser init)
- deps.sx: scan-*/transitive-* [] pure, compute-all-* [mutation]
- router.sx: all [] pure (URL matching)

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

shared/sx/ref/js.sx

@@ -1318,10 +1318,15 @@
 
 (define js-emit-define
   (fn (expr)
+    ;; Handle (define name :effects [...] value) — skip :effects annotation
     (let ((name (if (= (type-of (nth expr 1)) "symbol")
                   (symbol-name (nth expr 1))
                   (str (nth expr 1))))
-          (val-expr (nth expr 2)))
+          (val-expr (if (and (>= (len expr) 5)
+                             (= (type-of (nth expr 2)) "keyword")
+                             (= (keyword-name (nth expr 2)) "effects"))
+                      (nth expr 4)
+                      (nth expr 2))))
       (if (nil? val-expr)
         (str "var " (js-mangle name) " = NIL;")
         ;; Detect zero-arg self-tail-recursive functions → while loops