Implement explicit CEK machine, continuations, effect signatures, fix dynamic-wind and inspect shadowing

Three-phase foundations implementation:

Phase A — Activate dormant shift/reset continuations with 24 SX-native tests
covering basic semantics, predicates, stored continuations, nested reset,
scope interaction, and TCO.

Phase B — Bridge compile-time effect system to runtime: boundary_parser extracts
46 effect annotations, platform provides populate_effect_annotations() and
check_component_effects() for static analysis. 6 new type tests.

Phase C — Explicit CEK machine (frames.sx + cek.sx): evaluation state as data
({control, env, kont, phase, value}), 21 frame types, two-phase step function
(step-eval/step-continue), native shift/reset via frame capture. Bootstrapper
integration: --spec-modules cek transpiles to Python with iterative cek_run.
43 interpreted + 49 transpiled tests passing.

Bug fixes:
- inspect() shadowed by `import inspect` in PLATFORM_ASYNC_PY — renamed to
  `import inspect as _inspect`
- dynamic-wind missing platform functions (call_thunk, push_wind!, pop_wind!) —
  added with try/finally error safety via dynamic_wind_call

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

shared/sx/ref/boundary_parser.py

@@ -283,6 +283,58 @@ def parse_boundary_sx() -> tuple[frozenset[str], dict[str, frozenset[str]]]:
     return frozenset(all_io), frozen_helpers
 
 
+def parse_boundary_effects() -> dict[str, list[str]]:
+    """Parse boundary.sx and return effect annotations for all declared primitives.
+
+    Returns a dict mapping primitive name to its declared effects list.
+    E.g. {"current-user": ["io"], "reset!": ["mutation"], "signal": []}.
+
+    Only includes primitives that have an explicit :effects declaration.
+    Pure primitives from primitives.sx are not included (they have no effects).
+    """
+    source = _read_file("boundary.sx")
+    exprs = parse_all(source)
+    result: dict[str, list[str]] = {}
+
+    _DECL_FORMS = {
+        "define-io-primitive", "declare-signal-primitive",
+        "declare-spread-primitive",
+    }
+
+    for expr in exprs:
+        if not isinstance(expr, list) or len(expr) < 2:
+            continue
+        head = expr[0]
+        if not isinstance(head, Symbol) or head.name not in _DECL_FORMS:
+            continue
+
+        name = expr[1]
+        if not isinstance(name, str):
+            continue
+
+        effects_val = _extract_keyword_arg(expr, "effects")
+        if effects_val is None:
+            # IO primitives default to [io] if no explicit :effects
+            if head.name == "define-io-primitive":
+                result[name] = ["io"]
+            continue
+
+        if isinstance(effects_val, list):
+            effect_names = []
+            for item in effects_val:
+                if isinstance(item, Symbol):
+                    effect_names.append(item.name)
+                elif isinstance(item, str):
+                    effect_names.append(item)
+            result[name] = effect_names
+        else:
+            # Might be a single symbol
+            if isinstance(effects_val, Symbol):
+                result[name] = [effects_val.name]
+
+    return result
+
+
 def parse_boundary_types() -> frozenset[str]:
     """Parse boundary.sx and return the declared boundary type names."""
     source = _read_file("boundary.sx")