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/forms.sx

@@ -22,7 +22,7 @@
 ;; --------------------------------------------------------------------------
 
 (define parse-key-params
-  (fn (params-expr)
+  (fn ((params-expr :as list))
     (let ((params (list))
           (in-key false))
       (for-each
@@ -42,7 +42,7 @@
 ;; --------------------------------------------------------------------------
 
 (define sf-defhandler
-  (fn (args env)
+  (fn ((args :as list) (env :as dict))
     (let ((name-sym   (first args))
           (params-raw (nth args 1))
           (body       (nth args 2))
@@ -58,7 +58,7 @@
 ;; --------------------------------------------------------------------------
 
 (define sf-defquery
-  (fn (args env)
+  (fn ((args :as list) (env :as dict))
     (let ((name-sym   (first args))
           (params-raw (nth args 1))
           (name       (symbol-name name-sym))
@@ -77,7 +77,7 @@
 ;; --------------------------------------------------------------------------
 
 (define sf-defaction
-  (fn (args env)
+  (fn ((args :as list) (env :as dict))
     (let ((name-sym   (first args))
           (params-raw (nth args 1))
           (name       (symbol-name name-sym))
@@ -98,7 +98,7 @@
 ;; --------------------------------------------------------------------------
 
 (define sf-defpage
-  (fn (args env)
+  (fn ((args :as list) (env :as dict))
     (let ((name-sym (first args))
           (name     (symbol-name name-sym))
           (slots    {}))
@@ -106,7 +106,7 @@
       (let ((i 1)
             (max-i (len args)))
         (for-each
-          (fn (idx)
+          (fn ((idx :as number))
             (when (and (< idx max-i)
                        (= (type-of (nth args idx)) "keyword"))
               (when (< (+ idx 1) max-i)
@@ -195,28 +195,28 @@
 
 ;; Extract stream-id from a data chunk dict, defaulting to "stream-content"
 (define stream-chunk-id
-  (fn (chunk)
+  (fn ((chunk :as dict))
     (if (has-key? chunk "stream-id")
       (get chunk "stream-id")
       "stream-content")))
 
 ;; Remove stream-id from chunk, returning only the bindings
 (define stream-chunk-bindings
-  (fn (chunk)
+  (fn ((chunk :as dict))
     (dissoc chunk "stream-id")))
 
 ;; Normalize binding keys: underscore → hyphen
 (define normalize-binding-key
-  (fn (key)
+  (fn ((key :as string))
     (replace key "_" "-")))
 
 ;; Bind a data chunk's keys into a fresh env (isolated per chunk)
 (define bind-stream-chunk
-  (fn (chunk base-env)
+  (fn ((chunk :as dict) (base-env :as dict))
     (let ((env (merge {} base-env))
           (bindings (stream-chunk-bindings chunk)))
       (for-each
-        (fn (key)
+        (fn ((key :as string))
           (env-set! env (normalize-binding-key key)
                     (get bindings key)))
         (keys bindings))