Extend defhandler with :path/:method/:csrf, migrate 12 ref endpoints to SX

defhandler now supports keyword options for public route registration:
  (defhandler name :path "/..." :method :post :csrf false (&key) body)

Infrastructure: forms.sx parses options, HandlerDef stores path/method/csrf,
register_route_handlers() mounts path-based handlers as app routes.

New IO primitives (boundary.sx "Web interop" section): now, sleep,
request-form, request-json, request-header, request-content-type.

First migration: 12 reference API endpoints from Python f-string SX
to declarative .sx handlers in sx/sx/handlers/ref-api.sx.

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

shared/sx/ref/sx_ref.py

@@ -181,8 +181,14 @@ def make_macro(params, rest_param, body, env, name=None):
                  closure=dict(env), name=name)
 
 
-def make_handler_def(name, params, body, env):
-    return HandlerDef(name=name, params=list(params), body=body, closure=dict(env))
+def make_handler_def(name, params, body, env, opts=None):
+    path = opts.get('path') if opts else None
+    method = str(opts.get('method', 'get')) if opts else 'get'
+    csrf = opts.get('csrf', True) if opts else True
+    if isinstance(csrf, str):
+        csrf = csrf.lower() not in ('false', 'nil', 'no')
+    return HandlerDef(name=name, params=list(params), body=body, closure=dict(env),
+                      path=path, method=method.lower(), csrf=csrf)
 
 
 def make_query_def(name, params, doc, body, env):
@@ -1776,14 +1782,43 @@ def parse_key_params(params_expr):
                 params.append(name)
     return params
 
+# parse-handler-args
+def parse_handler_args(args):
+    _cells = {}
+    'Parse defhandler args after the name symbol.\n     Scans for :keyword value option pairs, then a list (params), then body.\n     Returns dict with keys: opts, params, body.'
+    opts = {}
+    _cells['params'] = []
+    _cells['body'] = NIL
+    _cells['i'] = 0
+    n = len(args)
+    _cells['done'] = False
+    for idx in range(0, n):
+        if sx_truthy(((not sx_truthy(_cells['done'])) if not sx_truthy((not sx_truthy(_cells['done']))) else (idx == _cells['i']))):
+            arg = nth(args, idx)
+            if sx_truthy((type_of(arg) == 'keyword')):
+                if sx_truthy(((idx + 1) < n)):
+                    val = nth(args, (idx + 1))
+                    opts[keyword_name(arg)] = (keyword_name(val) if sx_truthy((type_of(val) == 'keyword')) else val)
+                _cells['i'] = (idx + 2)
+            elif sx_truthy((type_of(arg) == 'list')):
+                _cells['params'] = parse_key_params(arg)
+                if sx_truthy(((idx + 1) < n)):
+                    _cells['body'] = nth(args, (idx + 1))
+                _cells['done'] = True
+            else:
+                _cells['body'] = arg
+                _cells['done'] = True
+    return {'opts': opts, 'params': _cells['params'], 'body': _cells['body']}
+
 # sf-defhandler
 def sf_defhandler(args, env):
     name_sym = first(args)
-    params_raw = nth(args, 1)
-    body = nth(args, 2)
     name = symbol_name(name_sym)
-    params = parse_key_params(params_raw)
-    hdef = make_handler_def(name, params, body, env)
+    parsed = parse_handler_args(rest(args))
+    opts = get(parsed, 'opts')
+    params = get(parsed, 'params')
+    body = get(parsed, 'body')
+    hdef = make_handler_def(name, params, body, env, opts)
     env[sx_str('handler:', name)] = hdef
     return hdef