Add (param :as type) annotations to all fn/lambda params across SX spec

Extend the type annotation system from defcomp-only to fn/lambda params:
- Infrastructure: sf-lambda, py/js-collect-params-loop, and bootstrap_py.py
  now recognize (name :as type) in param lists, extracting just the name
- bootstrap_py.py: add _extract_param_name() helper, fix _emit_for_each_stmt
- 521 type annotations across 22 .sx spec files (eval, types, adapters,
  transpilers, engine, orchestration, deps, signals, router, prove, etc.)
- Zero behavioral change: annotations are metadata for static analysis only
- All bootstrappers (Python, JS, G1) pass, 81/81 spec tests pass

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

shared/sx/ref/continuations.sx

@@ -82,7 +82,7 @@
 ;; --------------------------------------------------------------------------
 
 (define sf-reset
-  (fn (args env)
+  (fn ((args :as list) (env :as dict))
     ;; Single argument: the body expression.
     ;; Install a continuation delimiter, then evaluate body.
     ;; The implementation is target-specific:
@@ -136,7 +136,7 @@
 ;; --------------------------------------------------------------------------
 
 (define sf-shift
-  (fn (args env)
+  (fn ((args :as list) (env :as dict))
     ;; Two arguments: the continuation variable name, and the body.
     (let ((k-name (symbol-name (first args)))
           (body   (second args)))