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/bootstrap_py.py

@@ -664,7 +664,12 @@ class PyEmitter:
     def _emit_define(self, expr, indent: int = 0) -> str:
         pad = "    " * indent
         name = expr[1].name if isinstance(expr[1], Symbol) else str(expr[1])
-        val_expr = expr[2]
+        # Handle (define name :effects [...] value) — skip :effects annotation
+        if (len(expr) >= 5 and isinstance(expr[2], Keyword)
+                and expr[2].name == "effects"):
+            val_expr = expr[4]
+        else:
+            val_expr = expr[2]
         # Always emit fn-bodied defines as def statements for flat control flow
         if (isinstance(val_expr, list) and val_expr and
                 isinstance(val_expr[0], Symbol) and val_expr[0].name in ("fn", "lambda")):
@@ -675,7 +680,12 @@ class PyEmitter:
     def _emit_define_async(self, expr, indent: int = 0) -> str:
         """Emit a define-async form as an async def statement."""
         name = expr[1].name if isinstance(expr[1], Symbol) else str(expr[1])
-        val_expr = expr[2]
+        # Handle (define-async name :effects [...] value) — skip :effects annotation
+        if (len(expr) >= 5 and isinstance(expr[2], Keyword)
+                and expr[2].name == "effects"):
+            val_expr = expr[4]
+        else:
+            val_expr = expr[2]
         if (isinstance(val_expr, list) and val_expr and
                 isinstance(val_expr[0], Symbol) and val_expr[0].name in ("fn", "lambda")):
             return self._emit_define_as_def(name, val_expr, indent, is_async=True)