Step 18 (part 7): Extensions — render components + SX escape

Two hyperscript extensions beyond stock:

render ~component :key val [into|before|after target]
  Tokenizer: ~ + ident → component token type
  Parser: render command with kwargs and optional position
  Compiler: emits (render-to-html ~comp :key val) or
            (hs-put! (render-to-html ...) pos target)
  Bridges hyperscript flow to SX component rendering

eval (sx-expression) — SX escape hatch
  Inside eval (...), content is SX syntax (not hyperscript)
  Parser: collect-sx-source extracts balanced parens from raw source
  Compiler: sx-parse at compile time, inlines AST directly
  Result: SX runs in handler scope — hyperscript variables visible!
  Also supports string form: eval '(+ 1 2)' for backward compat

  set name to "Giles"
  set greeting to eval (str "Hello " name)  -- name is visible!

16 new tests (parser + compiler + integration).
3127/3127 full build, zero regressions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/hyperscript/compiler.sx

@@ -524,6 +524,45 @@
                     (map make-symbol (nth ast 2))
                     (hs-to-sx (nth ast 3)))))
               ((= head (quote behavior)) (emit-behavior ast))
+              ((= head (quote sx-eval))
+                (let
+                  ((src (nth ast 1)))
+                  (if
+                    (string? src)
+                    (first (sx-parse src))
+                    (list (quote cek-eval) (hs-to-sx src)))))
+              ((= head (quote component)) (make-symbol (nth ast 1)))
+              ((= head (quote render))
+                (let
+                  ((comp-raw (nth ast 1))
+                    (kwargs (nth ast 2))
+                    (pos (if (> (len ast) 3) (nth ast 3) nil))
+                    (target
+                      (if (> (len ast) 4) (hs-to-sx (nth ast 4)) nil)))
+                  (let
+                    ((comp (if (string? comp-raw) (make-symbol comp-raw) (hs-to-sx comp-raw))))
+                    (define
+                      emit-kw-pairs
+                      (fn
+                        (pairs)
+                        (if
+                          (< (len pairs) 2)
+                          (list)
+                          (cons
+                            (make-keyword (first pairs))
+                            (cons
+                              (hs-to-sx (nth pairs 1))
+                              (emit-kw-pairs (rest (rest pairs))))))))
+                    (let
+                      ((render-call (cons (quote render-to-html) (cons comp (emit-kw-pairs kwargs)))))
+                      (if
+                        pos
+                        (list
+                          (quote hs-put!)
+                          render-call
+                          pos
+                          (if target target (quote me)))
+                        render-call)))))
               (true ast))))))))
 
 ;; ── Convenience: source → SX ─────────────────────────────────